Integrated process for the manufacture of methylchlorohydridomonosilanes

ABSTRACT

The present invention relates to an integrated process for the manufacture of methylchlorohydridomonosilanes in particular, from products of the Müller-Rochow Direct Process.

The present invention relates to a new integrated process for themanufacture of methylchlorohydridomonosilanes selected from Me₂Si(H)Cl,MeSi(H)Cl₂, and MeSi(H)₂Cl, in particular, from products of the MüllerRochow Direct Process (MCS or DPR or Direct Synthesis, Rochow Process,or Müller-Rochow Process), in particular, from the entire product streamof the Müller Rochow Direct Process or from partial parts or fractionsof the Müller Rochow Direct Process, such as the higher silane fractionsor so-called DPR residues. By the process of the present inventionmethylchlorohydridosilanes, especially key intermediates such asMe₂Si(H)Cl [M2H] or MeSi(H)Cl₂ [MH] can be produced morecost-effectively and with lower amounts of undesirable by-products.

Technical Problems

Key-intermediates in the manufacture of functionalized silicones are, inparticular, Me₂Si(H)Cl [M2H] or MeSi(H)Cl₂ [MH]. Due to their SiH groupsthey allow the functionalization of silicones such as PDMSbase-polymers, formed by hydrolysis and condensation or co-condensationvia the chloro substituent, to introduce e.g. organic functional groups.These organic functional groups may be used to adjust the properties ofthe final silicone product in a wide range. The organic functionalgroups are introduced by a catalyst-mediated hydrosilylation reactionwith unsaturated organic compounds. Therefore, an economic and easyaccess to such methylchlorohydridosilanes is of utmost importance toachieve a high diversification of the silicone product portfolio.

The MCS direct process (Müller-Rochow Process, MCS=methylchlorosilanes)itself does not deliver commercially sufficient volumes of theseenabling and desired SiH containing intermediates. All formed componentsneed to be separated by column distillation in order to isolate themethylchlorohydridosilanes of interest (e.g. M2H and MH). The unwantedcomponents of less value are subsequently re-introduced back into aredistribution process.

In fact, following the given chemistry of the redistribution, the MH(MeSi(H)Cl₂) and Mono (Me₃SiCl) need to be sacrificed in order toproduce the highly valued and more commercially desired intermediate M2H(see: MH+Mono→M2H+Di (Me₂SiCl₂). Moreover, by producing an equivalentvaluable M2H, also less desirable Me₂SiCl₂ [Di] is formed as well. Thus,the economy of the overall process can be assessed to be comparablyinefficient, and to date other large volume manufacturing routes are notavailable for these methylchlorohydridosilanes components.

JP H03 24091 A) describes a process of manufacturing R₂SiHCl bysubjecting R₂SiCl₂ to partial reduction in a molten salt comprisinglithium chloride and potassium chloride, using lithium hydride as areducing agent. In second embodiment in a first stepdialkyldichlorosilanes are produced by the complete reduction ofdialkyldichlorosilanes with lithium hydride in the presence of a metalmolten salt capable of forming a molten salt with lithium chloride, andthen in a separate step the dialkylsilanes thus produced and thedialkyldichlorosilanes used as raw materials are subjected to theredistribution reaction in a separate reactor to form R₂SiHCl in thepresence of a catalyst such as Lewis acid catalysts. The process in thereduction step requires high temperatures, and there is no pointer to aprocess which is carried out in a solvent, leaving alone a process,where reduction and redistribution are carried out simultaneously.

EP 0878476A1 relates to a process for preparing dimethylmonochlorosilane(CH₃)₂Si(H)Cl, wherein a reaction mixture comprisingdimethyldichlorosilane (CH₃)₂SiCl₂, magnesium hydride, and aluminumchloride, is subjected in an inert liquid organic vehicle, to thepartial hydrogenation of dimethyldichlorosilane. The presence of AlCl₃causes technical problems because it is difficult to separate from theproduct formed due to the high solubility in chlorosilanes and the lowsublimation temperature. Also the amount of the undesired dimethylsilaneis comparatively high.

A. J. CHALK, JOURNAL OF ORGANOMETALLIC CHEMISTRY, vol. 21, no. 1, 1 Jan.1970 discloses the reduction of a variety of chlorosilanes to thecorresponding silicon hydrides with sodium hydride inhexamethylphosphoric triamide (HMPT), tetramethylurea (TMU) and relatedsolvents. There is no description of the manufacture of Me₂Si(H)Cl,MeSi(H)Cl₂, or MeSi(H)₂Cl.

Gerard Simon ET AL, Journal of Organometallic Chemistry, 1 Jan. 1981,pages 279-286, teaches the partial reduction of MeSiCl₃ and Me₂SiCl₂using CaH₂ or (TiH₂)_(n) at high temperature (300° C.) which leads toMeSiHCl₂ and Me₂SiHCl in low proportion. In the presence of AlCl₃ ascatalyst the reaction promotes the formation of chlorosilanes Me₂SiCl₂and Me₃SiCl, whereby the amount of MeSiHCl₂ formed is lowered. Also thepresence of AlCl₃ causes technical problems because it is difficult toseparate from the product formed due to the high solubility inchlorosilanes and the low sublimation temperature.

CN 104 892 659 A discloses a method for synthesizingdialkylmonochlorosilane from dialkyldichlorosilane by reduction withaluminum hydride/aluminum chloride, lithium aluminum hydride/aluminumchloride, sodium hydride/aluminum chloride and aluminum hydride/lithiumaluminum hydride in the amido or ureido solvent methyl pyrrolidone,ethyl pyrrolidone, or N,N-dimethyl imidazolidinone. There is no pointerin such document that apart from the hydrogenation reaction aredistribution reaction occurs, and it is also expected that methylpyrrolidone, ethyl pyrrolidone, or N,N-dimethyl imidazolidinone do nothave sufficient nucleophilicity to catalyze the redistribution reaction.

U.S. Pat. No. 5,136,070 relates according to claim 1 to a process fordisproportionation of cycloorganosilanes in the presence of a sodiumborohydride catalyst. No methylsilanes are used as the startingmaterials.

EP0301678 relates to the selective and stepwise reduction ofpolyhalosilanes with alkyltin hydrides. In the reduction of (CH₃)SiCl₃with (CH₃)₃SnH only a trace of (CH₃)SiCl₂H is formed. No redistributionof the chloromethylsilanes takes place. Although redistribution isaddressed at some places in EP0301678, it refers solely to a halogenexchange in halogen silanes.

U.S. Pat. No. 3,627,803 relates to the reaction of aluminum alkyls withhalo and/or alkoxysilanes at 300° C. or above to give silanes containingSiH groups without alkylation of the silicon. There is redistributionstep in such document.

GB851013A relates to a method of reducing a reducible silicon compound,which comprises effecting reaction at a temperature of from 175° to 350°C. between sodium hydride and a silane. There is no indication of aredistribution step.

According to J E Hengge ET AL, Monatshefte fir Chemie, 1 Jan. 1995,pages 549-555, trialkyl tin hydrides such as Bu₃SnH can be used for thehydrogenation of Si—Cl bonds in mono- and disilanes, wherein, dependingon the catalyst required (tertiary amines, N-heterocycles, λ³-phosphoruscompounds, ammonium and phosphonium salts) only hydrogenated or (withstrongly nucleophilic catalysts), also the Si—Si bond can be cleaved. Inan example 1,2-dimethyltetrachlorodisilane and tri-n-butyl tin hydridelead to the formation of MeSi(H)Cl₂ (20%), MeSi(Cl)H₂ (40%) and MeSiH₃(10%) is obtained with a proportion of 70 to 80% of the total amount ofsilicon used and the reaction solution still contains residues of thestarting material as well as hydrogenated di- and oligosilanes. There isno indication of a redistribution reaction in such document, and arelative high excess of the trialkyl tin hydride is necessary. Moreoverthe amount of MeSiH₃ and byproducts is comparatively high, and tincatalysts are not desired from an environmental point of view.

MICHAEL N. MISSAGHI ET AL, ORGANOMETALLICS, vol. 27, no. 23, 8 Dec. 2008(2008 Dec. 8), pages 6364-6366, disclose the manufacture oforganofunctional silicon hydride halides R(CH₃)SiHCl. No hydrogenationstep is carried out.

RU 2 436 788 C1 discloses the reaction of trimethylchlorosilane withlithium hydride in the presence of tetrakis (diethylamido phosphoniumbromide) in toluene at 65-74° C. whereby trimethylsilane is formed. Noredistribution is described. US 2013/172593A1 does not disclose ahydrogenation step.

While redistribution reactions have been useful in providing access toalkylhydridohalosilanes, and specifically methyldichlorosilane [MH] anddimethylchlorosilane [M2H], these reactions depend on the limited supplyof by-products from the conventional Rochow-Müller Direct Process. Thelatter is operated to produce dimethyldichlorosilane as the mainproduct. Modifications of the Rochow-Müller Direct Process to increaseformation of methyldichlorosilane [MH] and dimethylchlorosilane [M2H]have been disclosed by Lewis, et al. in U.S. Pat. No. 4,973,725 and byHalm, et al., in U.S. Pat. Nos. 4,966,986 and 4,965,388. In all of thesedisclosures, methyldichlorosilane [MH] is produced in greater quantitythan dimethylchlorosilane [M2H]. However, what is needed is a processwith higher selectivity to dimethylchlorosilane [M2H]. Particularlydesirable is a process in which dimethylchlorosilane [M2H] is producedin excess relative to methyldichlorosilane [M2H]. The instant inventionseeks to fulfill this objective by reacting in particular the mixtureproduced via the conventional Rochow-Müller Direct Process with LiH toconvert the dominant constituent dimethyldichlorosilane [Di] todimethylchlorosilane [M2H]. Thereby, the product composition of theRochow-Müller Direct Process can be modified to increase selectivity tothe methylhydridochlorosilanes, and in particular, to also providedimethylchlorosilane in excess relative to methyldichlorosilane.

The technical object to be solved here in particular is to find aneconomically viable and efficient pathway to selectively formmethylhydridochlorosilanes in particular from the product or partialparts of the product of the Rochow-Müller Direct Process. The desiredproduct should lead to M2H and MH in high yields and should reduce theformation of undesirable by-products.

Solution of the Technical Problems

These objects have been surprisingly solved by a process for themanufacture of methylchlorohydridomonosilanes, selected from Me₂Si(H)Cl,MeSi(H)Cl₂, and MeSi(H)₂Cl, preferably Me₂Si(H)Cl, and MeSi(H)Cl₂, andmost preferably Me₂Si(H)Cl, which comprises: subjecting a silanesubstrate comprising at least one silane selected from the groupconsisting of:

(i) Monosilanes,

(ii) Disilanes,

(iii) Oligosilanes,

(iv) Carbodisilanes,

with the proviso that at least one of the silanes (i) to (iv) has atleast one chloro substituent,

-   a) to a hydrogenation reaction with at least one hydride donating    source, and-   b) to a redistribution reaction, and-   c) optionally to a cleavage reaction of the Si—Si bonds of the di-    or oligosilanes or the Si—C-bond of the carbodisilanes, and-   d) to a separating step of the methylchlorohydridosilanes,

wherein the process is carried out in the presence of one or moresolvents, preferably selected from ether solvents, in the absence ofAlCl₃, wherein

-   (i) the monosilanes are selected from the general formula (I),

Me_(x)SiH_(y)Cl_(z)  (I)

wherein

x=1 to 3,

y=0 to 3,

z=0 to 3, and

x+y+z=4,

-   (ii) the disilanes are selected from the general empirical formula    (II),

Me_(m)Si₂H_(n)Cl_(o)  (II)

-   -   wherein    -   m=1 to 6,    -   n=0 to 5    -   o=0 to 5 and    -   m+n+o=6,

-   (iii) oligosilanes are selected from linear or branched oligosilanes    of the general empirical formula (III)

Me_(p)Si_(q)H_(r)Cl_(s)  (III),

-   -   wherein    -   q=3-7    -   p=q to (2q+2)    -   r, s=0 to (q+2)    -   r+s=(2q+2)−p,

-   (iv) carbodisilanes are selected from the general formula (IV)

(Me_(a)SiH_(b)Cl_(e))—CH₂-(Me_(c)SiH_(d)Cl_(f))  (IV)

-   -   wherein    -   a, c are independently of each other 1 to 3,    -   b, d are independently from each other 0 to 2    -   e, f are independently from each other 0 to 2,    -   a+b+e=3,    -   c+d+f=3.

This integrated process allows in particular to transforming the entireor partial product stream(s) of the Müller Rochow Direct Processdirectly into the desired methylchlorohydridomonosilanes, in that itcombines a hydrogenation reaction with a redistribution reaction and—inparticular in the presence of the higher silane fraction(s) of theMüller Rochow Direct Process in the silane substrate—additionally acleavage reaction. That is, in a preferred embodiment of the inventionthe entire product streams of the Müller Rochow Direct Process aresubjected simultaneously in a one-pot reaction to a hydrogenationreaction, a cleavage reaction and a redistribution reaction by whichprocess the desired methylchlorohydridomonosilanes can be obtained andisolated in high yields. In a further particularly preferred embodimentlithium hydride (LiH) is used as the hydrogenation agent, which can beefficiently regenerated from the lithium chloride (LiCl) formed.

PREFERRED EMBODIMENTS OF THE INVENTION

According to the present invention, the term “redistribution reaction”describes the redistribution of hydrogen, chlorine substituents and/ororganyl groups, preferably of hydrogen and chlorine substituents, boundto silicon atoms of one or more silane compounds comprised in thereaction mixture by exchange of these substituents. The exchange can bemonitored in particular by ²⁹Si NMR, by GC and/or GC/MS. Theredistribution reactions are preferably catalyzed by the redistributioncatalysts described below.

The redistribution reaction of silanes in the context of the presentinvention includes in particular the comproportionation of two differentmethylsilanes (one having only chlorine as additional substituents, andone having only hydrogen as additional substituents) with the formationof one specific chlorohydridomethylsilane, such as, in particular:

Me₂SiCl₂+Me₂SiH₂⇒2Me₂SiHCl

2MeSiCl₃+MeSiH₃⇒3MeSiHCl₂

opposite to the undesired disproportionation where achlorohydridomethylsilane reacts to form two different methylsilanes(one having only chlorine as additional substituents, and one havingonly hydrogen as additional substituents):

2Me₂SiHCl→Me₂SiCl₂+Me₂SiH₂

3MeSiHCl₂⇒2 MeSiCl₃+MeSiH₃.

In preferred embodiment of the process according to invention, theredistribution reaction of silanes comprises the comproportionation oftwo different methylsilanes, in particular, of one methylsilane havingonly chlorine as additional substituents, and one methylsilane havingonly hydrogen as additional substituents, leading to the formation ofone specific chlorohydridomethylsilane.

In the present invention the silanes in the silane substrate subjectedto the process of the invention comprise at least one of the silanes ofthe group consisting of

-   (i) the monosilanes, which are selected from the general formula    (I),

Me_(x)SiH_(y)Cl_(z)  (I),

wherein

x=1 to 3,

y=0 to 3,

z=0 to 3, and

x+y+z=4,

-   (ii) the disilanes, which are selected from the general empirical    formula (II),

Me_(m)Si₂H_(n)Cl_(o)  (II)

-   -   wherein    -   m=1 to 6,    -   n=0 to 5    -   o=0 to 5 and    -   m+n+o=6,

-   (iii) the oligosilanes, which are selected from linear or branched    oligosilanes of the general empirical formula (III)

Me_(p)Si_(q)H_(r)Cl_(s)  (III),

-   -   wherein    -   q=3-7    -   p=q to (2q+2)    -   r, s=0 to (q+2)    -   r+s=(2q+2)−p, and

-   (iv) the carbodisilanes, which are selected from the general    empirical formula (IV)

(Me_(a)SiH_(b)Cl_(e))—CH₂-(Me_(c)SiH_(d)Cl_(f))  (IV)

-   -   wherein    -   a, c are independently of each other 1 to 3,    -   b, d are independently from each other 0 to 2    -   e, f are independently from each other 0 to 2,    -   a+b+e=3,    -   c+d+f=3,

with the proviso that at least one of the silanes of formulas (I) to(IV) has at least one chloro substituent.

In a preferred embodiment the silane substrate is consisting of thesilanes of formulas (I) to (IV). More preferably the silane substrate isMe₂SiCl₂.

The disilanes of the general empirical formula (II)

Me_(m)Si₂H_(n)Cl_(o)  (II)

can be depicted also by the structural formula:

wherein the substituents R′ are independently selected from methyl (Me),hydrogen (H) and chlorine (Cl), wherein the number of methyl m=1 to 6,the number of hydrogen atoms n=0 to 5 and the number of chlorine atomso=0 to 5, and the total of m+n+o=6.

The oligosilanes of the general formula (III)

Me_(p)Si_(q)H_(r)Cl_(s)  (III),

are oligosilanes that have a linear or branched silane skeleton, whereinq=3 to 7 silicon atoms are bonded to each other by single bonds, and thefree valencies of the silane skeleton are saturated by substituentsselected from methyl (Me), hydrogen (H) and chlorine (Cl) with theproviso that the number of methyl groups p=q to (2q+2), whichcorresponds to the case where each silicon atom has one methyl group(p=q) and the case of permethylated silanes (p=2q+2) and which meansthat there are at least 3 methyl groups up to 16 methyl groups (i.e. inSi₇Me₁₆) in the silanes; and the number of hydrogen atoms (r) andchlorine atoms (s) are independently of each other 0 to (q+2), andr+s=(2q+2)−p, wherein q is the number of silicone atoms and p is thenumber of methyl groups, again with the preferred proviso that each Siatom bears at least one methyl group.

In the entire application the meaning of the term “empirical formula”intends to mean that the formulae do not represent the structuralformulae, but just sum up the chemical groups or atoms present in themolecule. For example the empirical formula R₂Si₂Cl₄ may comprise thestructural formulae:

More preferably, in an embodiment, the silane substrate subjected to theprocess of the present invention comprises at least one of the followingsilanes:

(i) monosilanes, which are selected from the formulas:

MeSiCl₃, Me₂SiCl₂, Me₃SiCl, MeSiHCl₂, Me₂SiHCl, MeSiH₂Cl, MeSiH₃,Me₂SiH₂ and Me₃SiH,

(ii) disilanes, which are selected from the formulas:

Cl₂MeSi-SiMeCl₂, Cl₂MeSi-SiMe₂Cl, Cl₂MeSi-SiMe₃, ClMe₂Si—SiMe₂Cl,Me₃Si—SiMe₂Cl, HMe₂Si—SiMe₂Cl, H₂MeSi-SiMeClH, HClMeSi-SiMeClH,ClHMeSi-SiMeCl₂, H₂MeSi-SiMeCl₂, HMe₂Si—SiMeCl₂, ClMe₂Si—SiMeH₂,HMe₂Si—SiMeClH, ClMe₂Si—SiMeClH, Me₃Si—SiMeClH, HMe₂Si—SiMe₂H,H₂MeSi-SiMeH₂, HMe₂Si—SiMeH₂, Me₃Si—SiMeH₂ and Me₃Si—SiMe₂H,

(iii) oligosilanes, which are selected from the formulas:

ClMe₂Si—SiMe₂-SiMe₂Cl, ClMe₂Si—SiMe₂-SiMe₂-SiMe₂Cl, (ClMe₂Si)₃SiMe,(Cl₂MeSi)₂SiMeCl, (Cl₂MeSi)₃SiMe, (Cl₂MeSi)₂SiMe-SiClMe-SiCl₂Me,[(Cl₂MeSi)₂SiMe]₂, [(Cl₂MeSi)₂SiMe]₂SiClMe, (Cl₂MeSi)₂SiMe-SiMe₂Cl,ClMe₂Si—SiMe₂SiMe₂H, HMe₂Si—SiMe₂-SiMe₂H, HMe₂Si—SiMe₂-SiMe₂-SiMe₂H,(HMe₂Si)₃SiMe, (H₂MeSi)₂SiMeH, (H₂MeSi)₃SiMe,(H₂MeSi)₂SiMe-SiHMe-SiH₂Me, [(H₂MeSi)₂SiMe]₂, [(H₂MeSi)₂SiMe]₂SiHMe and(H₂MeSi)₂SiMe-SiMe₂H, and

(iv) carbodisilanes, which are selected from the formulas:

Cl₂MeSi—CH₂—SiMeCl₂, ClMe₂Si—CH₂—SiMeCl₂, ClMe₂Si—CH₂—SiMe₂Cl,Me₃Si—CH₂—SiMeCl₂Me₃Si—CH₂—SiMe₂Cl, HClMeSi—CH₂—SiMeClH,HMe₂Si—CH₂—SiMeCl₂, HMe₂Si—CH₂—SiMe₂Cl, Me₃Si—CH₂—SiMeClH,H₂MeSi—CH₂—SiMeH₂, HMe₂Si—CH₂—SiMeH₂, HMe₂Si—CH₂—SiMe₂H,Me₃Si—CH₂—SiMeH₂, and Me₃Si—CH₂—SiMe₂H, with the proviso that at leastone of the silanes used in the process has at least one chlorosubstituent.

More preferably the silane substrate subjected to the process of thepresent invention comprises at least two, preferably at least three,more preferably at least four silanes at least one of which, preferablyall of which having at least one chlorine substituent, preferablyselected from the above mentioned silanes.

In a preferred embodiment of the invention the silane substratecomprises at least one silane selected from the group consisting ofdisilanes (ii), oligosilanes (iii), and carbodisilanes (iv). In afurther preferred embodiment of the invention, the silane substratecomprises at least one, preferably more than one silane selected fromthe group consisting of MeSiCl₃, Me₂SiCl₂, Me₃SiCl, MeSiHCl₂, Me₂SiHCl,MeSiH₂Cl, MeSiH₃, Me₂SiH₂, Me₃SiH, Cl₂MeSi-SiMeCl₂, Cl₂MeSi-SiMe₂Cl,Cl₂MeSi-SiMe₃ClMe₂Si—SiMe₂Cl, Me₃Si—SiMe₂Cl, Cl₂MeSi—CH₂—SiMeCl₂,ClMe₂Si—CH₂—SiMeCl₂, ClMe₂Si—CH₂—SiMe₂Cl, Me₃Si—CH₂—SiMeCl₂ andMe₃Si—CH₂—SiMe₂Cl.

In a further preferred embodiment of the invention the silane substratecomprises one or more products (or product streams) preferably theentire product of the Müller-Rochow Direct Process.

The relevant reactions of the Müller-Rochow Direct Process are (Me=CH₃):x MeCl+Si→Me₃SiCl, Me₂SiCl₂, MeSiCl₃, and other products.

The major products of the Direct Process are monosilanes such as thoseof formula (I) above, in particular, dichlorodimethylsilane, Me₂SiCl₂,being obtained in about a 70-90 wt-% yield (wt=weight). The next mostabundant product is MeSiCl₃, at about 3-15 wt-% of the total amount.Other products include Me₃SiCl (about 2-about 4 wt-%), MeHSiCl₂ (about0.9-about 4 wt-%), Me₂HSiCl (about 0.1-about 0.5 wt-%). In anembodiment, these monosilanes are separated by fractional distillation.Up to about 10 wt-%-%, more preferably from about 0.1 to about 10 wt %of the Müller-Rochow Direct Process is formed of higher silanes such asthose of the formulas (II) to (IV) which are mostly disilanes.

Accordingly, a preferred silane substrate which is subjected to theprocess of the present invention comprises for example:

-   -   about 2 wt-% to about 10 wt-% higher silanes having more than        one silicon atom, such as those of the formulas (II) to (IV)        above, and    -   about 80 wt-% to 96 wt-% monosilanes, such as those of        formula (I) above.

each percentage being based on the entire amount of said silanes.

More specifically a preferred silane substrate which is subjected to theprocess of the present invention comprises for example:

-   -   Me₂SiCl₂: about 70 wt-%-about 90 wt-%    -   MeSiCl₃: about 3 wt-%-about 15 wt-%,    -   Me₃SiCl: about 2 wt-%-about 4 wt-%,    -   MeHSiCl₂: about 0.9 wt-%-about 4 wt-%,    -   Me₂HSiCl about 0.1 wt-%-about 0.5 wt-%, and    -   higher silanes, having more than such as those of the        formulas (II) to (IV): about 4 wt-% to about 10 wt-%,

each percentage being based on the entire amount of said silanes. Thesilane substrate may comprise other silanes not specifically mentionedhere in a total amount of e.g. up to 3 parts based on 100 parts of theabove composition, i.e. a composition of

-   -   Me₂SiCl₂: about 70 wt-%-about 90 wt-%    -   MeSiCl₃: about 3 wt-%-about 15 wt-%,    -   Me₃SiCl: about 2 wt-%-about 4 wt-%,    -   MeHSiCl₂: about 0.9 wt-%-about 4 wt-%,    -   Me₂HSiCl about 0.1 wt-%-about 0.5 wt-%, and    -   higher silanes, having more than such as those of the        formulas (II) to (IV): about 4 wt-% to about 10 wt-%.

In a further preferred embodiment of the invention the silane substratewhich is subjected to the process of the present invention is the entireproduct of the Müller-Rochow Direct Process or a part (fraction orproduct stream) of the product of the Müller-Rochow Direct Process.

The most preferred embodiment of the invention is to subject the entireproduct of the Müller-Rochow Direct Process to the process of thepresent invention.

In a further preferred embodiment of the invention the silane substratewhich is subjected to the process of the present invention comprises oneor more or the entire monosilane fraction of the Müller-Rochow DirectProcess product.

It is also possible to subject only a silane substrate which is a partor all of the higher silane fraction (silanes having ≥2 Si atoms) of theMüller-Rochow Direct Process product to the process of the presentinvention.

It is also possible to subject only a silane substrate, which is theoligosilane fraction (silanes having ≥3 Si atoms) and the carbodisilanefraction of the Müller-Rochow Direct Process product to the process ofthe present invention.

In a further preferred embodiment of the invention the silane substratesubjected to the process of the present invention is the higher silanefraction (silanes having ≥2 Si atoms) of the Müller-Rochow DirectProcess product, from which at least one component has been separatedcompletely or partially, and which component is preferably selected fromthe group consisting of disilanes having ≥3 chlorine atoms, anddisilanes having ≥3 methyl groups.

In a further preferred embodiment of the present invention the silanesubstrate comprises a product or a fraction of the Müller-Rochow DirectProcess product, from which at least one component has been separatedcompletely or partially, which component is selected from the groupconsisting of Me_(n)SiCl_(4-n), wherein n=1-3, Me₂Si(H)Cl, MeSi(H)Cl₂,and MeSi(H)₂Cl.

That is, in an embodiment one or more monosilanes, considered of beingvaluable according to current demands, including in particular thedesired methylchlorohydridosilanes (Me₂Si(H)Cl, MeSi(H)Cl₂, and/orMeSi(H)₂Cl) are separated before the remainder of the Müller-RochowDirect Process product is subjected to the process of the presentinvention.

In a further preferred embodiment of the present invention it is alsopossible to carry out at first the hydrogenation reaction a) andthereafter—before the redistribution and the optional cleavage step, themethylchlorohydridosilanes are separated from the reaction mixture.

The process of the present invention is preferably carried out in thepresence of one or more solvents, preferably selected from ethersolvents.

According to the present invention, the ether solvents can be selectedfrom ether compounds, preferably selected from the group consisting oflinear and cyclic aliphatic ether compounds.

In the present invention, the term “ether compound” shall mean anyorganic compound containing an ether group —O—, in particular of formulaR¹—O—R², wherein R¹ and R² are independently selected from an organylgroup R.

Preferably, in the present invention R represents an organyl group,which is bound to the silicon atom via a carbon atom, and which organylgroup can be the same or different.

Preferably the organyl group is an optionally substituted, morepreferably unsubstituted group, which is selected from the groupsconsisting of: alkyl, aryl, alkenyl, alkynyl, alkaryl, aralkyl,aralkenyl, aralkynyl, cycloalkyl, cycloalkenyl, cycloalkynyl,cycloaralkyl, cycloaralkenyl, and cycloaralkynyl, even more preferablyselected from alkyl, cycloalkyl, alkenyl and aryl, even furtherpreferred selected from methyl, vinyl and phenyl, and most preferably Ris a methyl group (herein abbreviated as Me).

Preferably, R¹ and R² are substituted or unsubstituted linear orbranched alkyl groups or aryl groups, which may have further heteroatomssuch as oxygen, nitrogen, or sulfur. In the case of cyclic ethercompounds, R¹ and R² can constitute together an optionally substitutedalkylene or arylene group, which may have further heteroatoms such asoxygen, nitrogen, or sulfur.

The ether compounds can be symmetrical or asymmetrical with respect tothe substituents at the ether group —O—.

In another preferred embodiment of the process of the present invention,the organic solvent in which step A) is conducted is a mixture of one ormore ether compounds and one or more non-ether compounds.

Preferably, the one or more non-ether compounds forming the mixture withone or more ether compounds are selected from solvents which are lesspolar than the ether compounds used, particular preferably fromaliphatic or aromatic hydrocarbons.

In a further preferred embodiment of the process according to theinvention, the ether compounds used as solvents are selected from thegroup of linear, cyclic or complexing ether compounds.

Herein, a linear ether compound is a compound containing an ether groupR¹—O—R² as defined above, in which there is no connection between the R¹and R² group except the oxygen atom of the ether group, as for examplein the symmetrical ethers Et₂O, n-Bu₂O, Ph₂O or diisoamyl ether(i-Pentyl₂O), in which R¹=R², or in unsymmetrical ethers as t-BuOMe(methyl t-butyl ether, MTBE) or PhOMe (methyl phenyl ether, anisol).

A cyclic ether compound used as solvent is a compound in which one ormore ether groups are included in a ring formed by a series of atoms,such as for instance tetrahydrofurane, tetrahydropyrane or 1,4-dioxane,which can be substituted e.g. by alkyl groups.

In linear ether compounds, also more than one ether group may beincluded forming a di-, tri-, oligo- or polyether compound, wherein R¹and R² constitute organyl groups when they are terminal groups of thecompounds, and alkylene or arylene groups when they are internal groups.Herein, a terminal group is defined as any group being linked to oneoxygen atom which is part of an ether group, while an internal group isdefined as any group linked to two oxygen atoms being a constituent ofether groups.

Preferred examples of such compounds are dimethoxy ethane, glycoldiethers (glymes), in particular diglyme or tetraglyme, without beinglimited thereto.

In the sense of present invention, the term “complex ether” isunderstood as an ether compound as defined above which is capable ofcomplexing cations, preferably metal cations, more preferably alkali andalkaline metal cations, even more preferably alkaline metal cations, andmost preferably lithium cations. Preferred examples of such complexethers according to the invention are glycol diethers (glymes), inparticular diglyme, triglyme, tetraglyme or pentaglyme, or crown ethers,in particular 12-crown-4, 15-crown-5, 18-crown-6, dibenzo-18-crown-6,and diaza-18-crown-6 without being limited thereto.

The term “complexing ether” is understood equivalently to the term“complex ether”.

In another preferred embodiment of the process according to theinvention, the ether compound is used as solvent and is selected fromthe group consisting of linear ethers, such as diethyl ether, di-n-butylether, complexing ethers, such as dimethoxy ethane, diethylene glycoldimethyl ether (diglyme) or tetraethylene glycoldimethyl ether(tetraglyme), alkylated polyethylene glycols (alkylated PEGs), cyclicethers such as dioxane, preferably 1,4-dioxane,2-methyltetrahydrofurane, tetrahydrofurane, or tetrahydropyrane.

In a particularly preferred embodiment of the process according to theinvention, the ether compound is a high-boiling ether compound,preferably diglyme or tetraglyme.

According to the present invention, the term “high-boiling ethercompound” is defined as an ether compound according to above definitionwith a boiling point at 1.01325 bar (standard atmosphere pressure) ofpreferably at least about 70° C., more preferably at least about 85° C.,even more preferably at least about 100° C., and most preferably atleast about 120° C.

High-boiling ethers can facilitate separation of the desired productsfrom the reaction mixture containing the solvent and residual startingmaterials. The products in general have lower boiling points than thestarting materials, and the boiling points of these products are alsolower than the boiling point of high-boiling ethers of above definition.

For instance, the respective boiling points (standard atmospherepressure) of selected representative products are about 35° C.(Me₂SiHCl), and about 41° C. (MeSiHCl₂), while a representativehigher-boiling ether compound diglyme has a boiling point of about 162°C., and the boiling point of unreacted methylchlorodisilanes principallycomposed of isomers of trimethyltrichlorodisilane anddimethyltetrachlorodisilanes is about 151 to about 158° C.

Application of higher-boiling ether compounds as solvents allows higherreaction temperatures to be utilized and simplifies separation of thedesired products from the reaction mixture by distillation.

According to the present invention, the term “hydrogenation reaction a)”refers to the exchange of one or more chlorine substituents at thesilicon atoms of the silane substrate by the same number of hydrogensubstituents.

According to the present invention, the term hydride donating sourcerefers to any compound which is capable of donating at least one hydrideanion in a reaction of the hydride donating source and a substrateaccording to the invention leading to the conversion of at least oneSi—Cl bond to a Si—H bond.

In an embodiment, preferably, the hydrogenation reaction a) of theprocess according to the invention is performed with a hydride donatingsource selected from the group of metal hydrides, therein preferablyfrom binary metal hydrides, such as LiH, NaH, KH, CaH₂ or MgH₂, complexmetal hydrides, such as LiAlH₄ or NaBH₄, and organometallic hydridereagents, such as n-Bu₃SnH, i-Bu₂AlH or sodium bis(2-methoxyethoxy)aluminum hydride, or a hydride donating source selected fromboron-containing hydride donors, more preferably selected fromorganohydridoboranes, hydridoboranates, hydridoboronates andhydridoborates, even more preferably hydridoboranates, hydridoboronatesand hydridoborates generated from the corresponding boranates, boronatesand borates being the Lewis acid part of a frustrated Lewis acid/Lewisbase pair and H₂.

According to the present invention, the term metal hydride refers to anyhydride donating source containing at least one metal atom or metal ionand at least one hydride ion.

Binary metal hydrides according to the present invention are metalhydrides consisting of ions of one specific metal and hydride ionsexclusively.

Preferably, the metal hydrides according to the invention are selectedfrom binary metal hydrides, more preferably selected from alkali metalhydrides and alkaline earth metal hydrides, even more preferablyselected from the group of lithium hydride, sodium hydride, potassiumhydride, magnesium hydride, calcium hydride, even more preferably fromlithium hydride and sodium hydride, most preferably the metal hydride islithium hydride.

The term “complex metal hydrides” according to the invention refers tometal salts wherein the anions contain hydride anions. Typically,complex metal hydrides contain more than one type of metal or metalloid.As there is neither a standard definition of a metalloid nor completeagreement on the elements appropriately classified as such, according tothe present invention the term “metalloid” comprises the elements boron,silicon, germanium, arsenic, antimony, tellurium, carbon, aluminum,selenium, polonium, and astatine.

The term “organometallic hydride reagent” refers to compounds thatcontain bonds between carbon and metal atoms, and which are capable ofdonating at least one hydride anion in the hydrogenation reaction ofhydrogenation step a).

In the preferred embodiment of the invention the hydride donating sourceused to affect the hydrogenation reaction a) is selected from metalhydrides, most preferably lithium hydride.

In a preferred embodiment of the process according to the invention, theamount of the hydride donating source, in particular of the metalhydride, preferably LiH in the hydrogenation reaction a) in relation tothe silane substrate compounds of the general formulae (I), (II), (III)and (IV) is in the range of about 1 mol-% to about 600 mol-%, preferablyabout 1 to about 400 mol-%, more preferably about 1 to about 200 mol-%,most preferably about 25 to about 150 mol-%, based on the total molaramount of the chlorine atoms present in silane substrate compounds ofthe general formulae (I), (II), (III) and (IV). For the determination ofthis ratio, all compounds of the general formulae (I), (II), (III) and(IV) are considered, regardless if they are submitted with other silanesnot covered by those formulas.

More preferably, the amount of the hydride donating source, inparticular of the metal hydride, preferably LiH, in the hydrogenationreaction a) in relation to the silane substrate compounds of the generalformulae (I), (II), (III) and (IV), based on the total molar amount ofthe chlorine atoms present in silane substrate compounds of the generalformulae (I), (II), (III) and (IV) is less than about 100 mol-%,preferably less than about 90 mol-%, more preferably less than about 80mol-%, in order to leave sufficient chlorine for subsequentredistribution reactions to obtain the desired silanes.

Most preferably the amount of the hydride donating source, in particularof the metal hydride, preferably LiH, in the hydrogenation reaction a)in relation to the silane substrate compounds of the general formulae(I), (II), (III) and (IV), based on the total molar amount of thechlorine atoms present in silane substrate compounds of the generalformulae (I), (II), (III) and (IV) is less than about 75 mol-%.Preferably, for the synthesis of monohydrated silanes such as MeSiHCl₂and Me₂SiHCl, LiH should be used in stoichiometric deficit (preferablyless than about 50 mol-%, preferably less than about 25 mol %), for anincrease of the amount of the monosilane MeSiH₂Cl the molar amount ispreferably about 25 to about 75 mol %.

In a preferred embodiment of the invention the weight ratio of thehydride donating source, in particular, of the metal hydride, preferablyLiH, in the hydrogenation reaction a) in relation to the silanesubstrates compounds of the general formulae (I), (II), (III) and (IV)is in the range of about 1:100 to about 100:1, preferably 10:90 to about90:10, more preferably 20:80 to about 80:20.

Herein, the weight ratio is defined as

m (hydride donating source, in particular, of the metal hydride,preferably LiH)/m (silane substrate compounds of the general formulae(I) (II), (III) and (IV). For the determination of this ratio, allcompounds of the general formulae (I), (II), (III) and (IV) areconsidered, regardless if they are submitted with other silanes notcovered by those formulas.

In another preferred embodiment of the process according to theinvention, the weight ratio of the silane substrates to the organicsolvent is in the range of about 0.01 to about 100, preferably in therange of about 0.1 to about 10, more preferably about 0.5 to about 4,most preferably about 0.5 to about 1.

Herein, the weight ratio is defined as m (silane substrate compounds ofthe general formulae (I), (II), (III) and (IV)/m (organic solvents).

For the determination of this ratio, all compounds of the generalformulae (I), (II), (III) and (IV) are considered, regardless if theyare submitted with other silanes not covered by those formulas.

In a preferred embodiment of the invention an optional cleavage reactionc) of the Si—Si bonds of the di- or oligosilanes or the Si—C-bond of thecarbodisilanes is carried out, preferably in a one pot reactionsimultaneously with the hydrogenation reaction a) and the redistributionreaction b). Such a cleavage reaction c) may only be suitable if thesilane substrate comprises, (ii) disilanes, (iii) oligosilanes, and/or(iv) carbodisilanes having at least one chloro substituent in at leastone silane.

In the process of the present invention the redistribution reaction b)is carried out in the presence of at least one redistribution catalyst.

As described above, in the present invention, the term “redistributionreaction b)” describes the redistribution of in particular hydrogen andchlorine substituents bound to silicon atoms of one or more compoundscomprised by the silane substrate by the exchange of the substituents.Also an exchange of the methyl groups is possible but normally notdesired or to be avoided.

Preferably, by the redistribution reaction b) from silanes bearing onlychlorine substituents at the silicon atoms and silanes bearing onlyhydrogen substituents at the silicon atoms and/or from silanes havinghydrogen and chlorine substituents at the silicon atoms, formed underreaction conditions, the yield of the desiredmethylchlorohydridomonosilanes is increased.

In the present invention the redistribution catalysts are normallydifferent from the solvent used in the reaction. In some instances theredistribution catalysts can also act as hydride donating source, inparticular, in the case of metal hydrides, but preferably theredistribution catalysts are different from the hydride donating source.In some instances the redistribution catalysts can also act as cleavagecatalysts, but it is also possible to use a different redistributioncatalyst and cleavage catalyst.

Redistribution catalysts are in particular compounds that catalyze thefollowing reactions:

Me₂SiCl₂+Me₂SiH₂⇒2Me₂SiHCl

2MeSiCl₃+MeSiH₃⇒3 MeSiHCl₂

in particular the reaction

Me₂SiCl₂+Me₂SiH₂⇒2Me₂SiHCl

at a given temperature. For example, if Me₂SiCl₂ and Me₂SiH₂ do notreact at a certain temperature but do react at that temperature in thepresence of a compound, then said compound acts as a redistributioncatalyst.

Preferably the redistribution catalysts are selected from the groupconsisting of:

-   -   R₄PCl, wherein R is hydrogen or an organyl group, which can be        the same or different, more preferably an aromatic group or        aliphatic hydrocarbon group, even more preferably a n-alkyl        group, and most preferably a n-butyl group,    -   triorganophosphines, wherein R is hydrogen or an organyl group,        preferably PPh₃ or n-Bu₃P,    -   triorganoamines, wherein R is an organyl group, preferably        n-Bu₃N or NPh₃,    -   N-heterocyclic amines, preferably non-N-substituted        methylimidazoles, such as 2-methylimidazole, and        4-methylimidazole, preferred are N-heterocyclic amines with a        free nucleophilic electron pair at the nitrogen atom, which        means that the nucleophilicity at the nitrogen atom in such        N-heterocyclic amines is not reduced by inductive or mesomeric        interactions. In particular, cyclic amides are normally not        suitable as redistribution catalysts,    -   quaternary ammonium compounds, preferably n-Bu₄NCl,    -   an alkali metal halide,    -   an alkaline earth metal halide,    -   an alkali metal hydride, and    -   an alkaline earth metal hydride.

In an embodiment, one or more redistribution catalysts can be used, inparticular, a combination of two redistribution catalysts is preferred.

As metal hydrides may also act as redistribution catalysts, it may notbe necessary to add a redistribution catalyst in addition to the hydridedonating source added in the hydrogenation reaction a). However,normally the addition of a redistribution catalyst in addition to thehydride donating source added in the hydrogenation reaction a) ispreferred. According to the preferred sequences of reactions a)hydrogenation reaction, b) redistribution reaction, and c) cleavagereaction, it is preferred that the redistribution catalyst is addedtogether with the hydride donating source and the optional cleavagecatalyst.

It may be that the redistribution catalyst also acts as a cleavagecatalyst, as described below, at the same time.

In a preferred embodiment the redistribution catalyst is selected fromthe group of:

-   -   R₄PCl, wherein R is hydrogen or an organyl group, which can be        the same or different, more preferably an aromatic group or        aliphatic hydrocarbon group, even more preferably a n-alkyl        group, and most preferably a n-butyl group,    -   triorganophosphines, wherein R is hydrogen or an organyl group,        preferably PPh₃,    -   triorganoamines, wherein R is an organyl group, preferably        n-Bu₃N,    -   N-heterocyclic amines, preferably non-N-substituted        methylimidazoles, such as 2-methylimidazole, and        4-methylimidazole, preferred are N-heterocyclic amines with a        free nucleophilic electron pair at the nitrogen atom, which        means that the nucleophilicity at the nitrogen atom in such        N-heterocyclic amines is not reduced by inductive or mesomeric        interactions. In particular, cyclic amides are normally not        suitable as redistribution catalysts, and    -   quaternary ammonium compounds, preferably n-Bu₄NCl.

In preferred redistribution catalysts selected from the compounds of thegeneral formula R₄PCl, R is hydrogen or an organyl group and R can bethe same or different, preferably R is an aromatic group, such asphenyl, tolyl, and/or an aliphatic hydrocarbon group, more preferably Ris an alkyl group, such as methyl, ethyl, n-, or iso propyl, n-butyl,sec-butyl, isobutyl, tert-butyl, n-pentyl, tert-pentyl, neopentyl,isopentyl, sec-pentyl, n-, iso or sec-hexyl n-, iso or sec-heptyl, n-,iso or sec-octyl etc., even more preferably R is a n-alkyl group, andmost preferably the compound of the general formula R₄PCl is n-Bu₄PCl.

In preferred redistribution catalysts selected from triorganophosphinesPR₃, R is hydrogen or an organyl group and can be the same or different,more preferably R is an alkyl such as described before, cycloalkyl oraryl group, most preferably the organophosphine is PPh₃ or n-Bu₃P.

In preferred redistribution catalysts selected from triorganoamines NR₃,R is an organyl group, more preferably R is an alkyl group, and mostpreferably the triorganoamine is n-Bu₃N or NPh₃.

Preferred redistribution catalysts selected from N-heterocyclic aminesare non-N-substituted methylimidazoles such as 2-methylimidazole, and4-methylimidazole, most preferably 2-methylimidazole.

In preferred redistribution catalysts selected from quaternary ammoniumcompounds NR₄Cl, R is an organyl group and can be the same or different,more preferably R is an alkyl group, and most preferably the quaternaryammonium compound is n-Bu₄NCl.

In a preferred embodiment of the present invention a combination ofquaternary ammonium compounds NR₄Cl and methylimidazoles can be used ascatalysts.

In a preferred embodiment of the present invention the optional cleavagereaction c) is carried out in the presence of at least one cleavagecatalyst. Preferred cleavage catalysts are selected from the groupconsisting of:

-   -   a quaternary Group 15 onium compound R₄QX, wherein each R is        independently a hydrogen or an organyl group, Q is phosphorus,        arsenic, antimony or bismuth, and X is a halide selected from        the group consisting of F, Cl, Br and I,    -   a heterocyclic amine,    -   a heterocyclic ammonium halide,    -   a mixture of R₃P and RX,

wherein R is as defined above, and X is as defined above,

-   -   alkali metal halide,    -   an alkaline earth metal halide,    -   an alkali metal hydride,    -   alkaline earth metal hydride or mixtures thereof, and optionally        in the presence of hydrogen chloride (HCl).

It is evident that the definitions of the redistribution catalysts andthe cleavage catalyst or compounds may overlap. Accordingly, as statedabove, compounds acting as redistribution catalysts may also act ascleavage catalysts and vice versa. In a preferred embodiment of theinvention the redistribution catalysts also act as cleavage catalyst orcompounds. It is further to be understood that also the hydride donatingsources, in particular the metal hydrides, such LiH may act as cleavagecompounds.

The cleavage reaction is used to describe the transformation by whichdisilanes (ii) such as represented by the general formula (II),oligosilanes (iii) such as represented by the general formula (III) andcarbodisilanes (iv) such as represented by the general formula (IV) arereacted to produce monomeric silanes. In the case of disilanes of thegeneral formula (II) and oligosilanes of the general formula (III), theterm “cleavage reaction of the silicon-silicon bond(s)” furtherindicates that according to the present invention, the cleavage of theaforementioned substrates is effected by breaking the bond connectingthe silicon atoms of these disilanes and oligosilanes. In the case ofcarbodisilanes of the general formula (III), the term “cleavage reactionof the silicon-carbon bonds” indicates that the cleavage reaction iseffected by breaking one or both bonds between the silyl groups of thecompounds and the methylene group linking the silyl groups. Suchcleavage processes comprise in particular hydrochlorination andhydrogenolysis reactions.

The cleavage reaction is preferably carried out in the presence of oneor more cleavage catalyst compounds.

Preferably, the cleavage catalysts compounds are selected from the groupof

-   -   a quaternary Group 15 onium compound R₄QX, wherein each R is        independently a hydrogen or an organyl group, Q is phosphorus,        arsenic, antimony or bismuth, and X is a halide selected from        the group consisting of F, Cl, Br and I,    -   a heterocyclic amine,    -   a heterocyclic ammonium halide,    -   a mixture of R₃P and RX, wherein R is as defined above, and X is        as defined above,    -   alkali metal halides,    -   alkaline earth metal halides,    -   alkali metal hydride or alkaline earth metal hydride, and        optionally    -   in presence of hydrogen chloride (HCl).

and

mixtures of the above-mentioned compounds.

It has been found that the cleavage catalysts under certain conditionsalso can act as reactants, i.e. they are consumed in the cleavagereactions, and that by virtue of this the amount of desirablehydridomonosilanes, such as Me₂SiHCl in particular, is significantlyincreased. Therefore, the cleavage catalysts are sometimes also referredto as cleavage compounds.

The cleavage reaction under certain circumstances may be also affectedin the presence of hydrogen chloride (HCl), in particular, in thepresence of hydrogen chloride and an ether compound such as the ethersolvents described above.

Preferred cleavage catalysts or cleavage compounds include, but are notlimited to:

-   -   phosphonium chlorides R₄PCl, wherein R is hydrogen or an organyl        group, which can be the same or different, more preferably an        aromatic group or aliphatic hydrocarbon group, even more        preferably a n-alkyl group, and most preferably a n-butyl group,    -   N-heterocyclic amines, more preferably methylimidazoles, such as        2-methylimidazole, 4-methylimidazole and 1-methylimidazole, and    -   quaternary ammonium compounds, more preferably n-Bu₄NCl,    -   and mixtures thereof.

As explained above, it may be that hydrogenation reaction a),redistribution reaction b) and cleavage reaction c) may be affected byonly adding the hydride donating source, because the hydride donatingsource or the reaction products thereof such as metal halides may alsoact as catalysts for the redistribution reaction b) and the cleavagereaction c); optionally HCl may be added to support the cleavagereaction.

Regarding the molar ratio of the redistribution catalyst in relation tothe silane substrate compounds it is preferably in the range of about0.0001 mol-% to about 600 mol-%, more preferably about 0.01 mol-% toabout 20 mol-%, even more preferably about 0.05 mol-% to about 2 mol-%,and most preferably about 0.05 mol-% to about 1 mol-%.

Herein, the molar ratio in % is defined as [n (molar amount of theredistribution catalyst)/n (molar amount of the silane substratecompounds of the general formulae (I), (II), (III) and (IV))]×100.

For the determination of this ratio, all redistribution catalysts areconsidered, and all silane substrate compounds of the general formulae(I), (II), (III) and (IV), regardless if they are submitted as a part ofa mixture comprising other silane compounds, which do not fall under thegeneral formulae (I), (II), (III) or (IV).

Likewise the molar ratio of the cleavage catalyst in relation to thesilane substrate compounds is preferably in the range of about 0.0001mol-% to about 600 mol-%, more preferably about 0.01 mol-% to about 20mol-%, even more preferably about 0.05 mol-% to about 2 mol-%, and mostpreferably about 0.05 mol-% to about 1 mol-%.

Herein, the molar ratio in % is defined as

[n (molar amount of the cleavage catalyst)/n(molar amount of the silanesubstrate compounds of the general formulae (I), (II), (III) and(IV))]×100.

These amounts also apply in case that a compound is applied which actsas both a redistribution catalyst and as cleavage catalyst compound.

In a preferred embodiment according to the invention the redistributioncatalyst has the formula R₄PCl.

Preferably, in the formula R₄PCl, R is a hydrogen or an organyl groupwhich can be the same or different, more preferably R is an aromaticgroup or an aliphatic hydrocarbon group, even more preferably R is analkyl or cycloalkyl group, even further preferably R is a n-alkyl group,and most preferably the compound of the general formula R₄PCl isn-Bu₄PCl.

In another preferred embodiment according to the invention, thecompounds of formula R₄PCl are formed in situ from compounds of theformulae R₃P and RCl, wherein R is H or an organyl group.

According to the invention, R in R₄PCl formed in situ can be the same ordifferent, and preferably R is the same and RCl is HCl or achloroalkane, more preferably RCl is a 1-chloroalkane with up to about20 carbon atoms, even more preferably RCl is a 1-chloroalkane with up toabout 10 carbon atoms, and most preferably RCl is 1-chlorobutane.

The term “formed in situ” as used herein means that the compound R₄PClis formed from R₃P and RCl by combination of the compounds in thereaction vessel in which reaction step A) is performed.

In an also preferred embodiment according to the invention, the processis carried out in the presence of at least one compound of the formulaR₄PCl and lithium hydride.

Preferably, the invention is carried out in the presence of lithiumhydride and at least one compound of the formula R₄PCl, wherein R is anorganyl group and can be the same or different.

In a further preferred embodiment according to the invention, theprocess is carried out in the presence of n-Bu₄PCl.

In the present invention, n-Bu₄PCl was found to be a particularlyeffective redistribution catalyst.

Preferably, the invention is carried out in the presence of n-Bu₄PCl andin the presence of lithium hydride as alkaline metal hydride, morepreferably in the presence of lithium hydride and a high-boiling ethercompound, most preferably in the presence of lithium hydride and ahigh-boiling ether compound selected from the group of diglyme,tetraglyme and 1,4-dioxane.

In a preferred embodiment of the present invention the hydrogenationreaction a), the redistribution reaction b), and optionally the cleavagereaction c) are carried out simultaneously and/or stepwise, preferablysimultaneously.

In a most preferred embodiment the entire product composition of aMüller-Rochow Direct Process is subjected to the simultaneoushydrogenation reaction a), redistribution reaction b), and cleavagereaction c), and from the resulting product the desiredmethylchlorohydridomonosilanes are isolated by fractional distillation.

However, depending on the particular silane substrate used in theprocess of the present invention specifically adapted reaction sequencescan be selected for example from one or more of the following processoptions:

-   -   the hydrogenation reaction a) and the redistribution reaction b)        are carried out simultaneously, the optional cleavage        reaction c) is carried out subsequently,    -   the hydrogenation reaction a), the redistribution reaction b)        and the cleavage reaction c) are carried out simultaneously,    -   at first the hydrogenation reaction a) is carried out        separately, and then the redistribution reaction b) and        optionally the cleavage reaction c) are carried out        simultaneously or separately, optionally in this embodiment        after the hydrogenation reaction a) the already formed        methylchlorohydridomonosilanes can be separated, before inducing        the redistribution reaction b) and the optional cleavage        reaction c),    -   at first the hydrogenation reaction a) is carried out, then        optionally the cleavage reaction c) is carried out, and then the        redistribution reaction b) is carried out, optionally in this        embodiment after the hydrogenation reaction a) the already        formed methylchlorohydridomonosilanes can be separated, before        inducing the cleavage reaction c) and the redistribution        reaction b),    -   the silane substrate is selected from monosilanes, and such        substrate is subjected first to the hydrogenation reaction a),        and subsequently to the redistribution reaction b), or such        substrate is subjected to the hydrogenation reaction a), and the        redistribution reaction b) simultaneously.

It is evident that if a monosilane substrate (such as the monosilanes offormula (I)) is applied that the cleavage reaction is normallydispensable.

The integrated process of the present invention to prepare themethylchlorohydridomonosilanes thus offers a great flexibility towardsany kind of chlorine-containing silane substrates as described above asobtained in particular as product (or partial product) of theMüller-Rochow Direct Process.

In a preferred embodiment of the present invention the process comprisesthe additional step of separating the monosilanes having more than onehydrogen atom, in particular, the perhydrated methylmonosilanes, such asMe₂SiH₂ and MeSiH₃, which are then subjected to a reaction selected fromthe group consisting of:

-   -   a chlorination reaction, preferably with ether/HCl, and/or    -   a redistribution reaction with silanes comprising at least one        chlorine atom, for which    -   the redistribution catalysts can be used as described above.

In this embodiment also the solvents can be applied as described above.

In another preferred embodiment of the present invention the processcomprises the additional step of separating disilanes and/oroligosilanes each having at least one hydrogen atom, which are thensubjected to a reaction, selected from the group consisting of:

-   -   a cleavage reaction, preferably in the presence ether/HCl,        and/or    -   a redistribution reaction with silanes comprising at least one        chlorine atom.

In these reactions the redistribution catalysts and the cleavagecatalyst and also the solvents as described above can be applied.

In a further preferred embodiment of the invention the process comprisesthe step of separating carbodisilanes having at least one hydrogen atom,which are then subjected to a reaction selected from the groupconsisting of:

-   -   a cleavage reaction, preferably in the presence of a metal        hydride, and/or    -   a redistribution reaction with silanes comprising at least one        chlorine atom.

For those reactions the metal hydrides, the redistribution catalysts andsolvents each as described above can be used.

If Me₃SiH is desired as a by-product, in a further preferred embodimentof the present invention the process comprises the step of separatingMe₃SiH, in particular, after the hydrogenation reaction a).

As described above in an embodiment of the process of the presentinvention the most preferred hydride donating source is LiH, which isconverted into lithium chloride (LiCl).

In a particular preferred embodiment of such process using lithiumhydride the LiCl formed is separated and subjected to the steps ofpurification, optionally mixing with KCl to prepare the LiCl—KCleutectic composition, electrolysis of the eutectic or molten LiCl toobtain metallic Li and regeneration of LiH from the Li so prepared.

It is the particular advantage of this embodiment that it renders theprocess of the present invention economical and efficient including inparticular in the conversion reaction (Di→M2H), by recycling andvalorizing the accruing LiCl and converting it back into LiH.

Therefore, the costs of the Li-metal appearing in both components (LiHand LiCl) is eliminated from the overall cost consideration and only theconversion costs involved in converting LiCl back into LiH is to beconsidered. In addition, the recycling is going along with the incumbentmanufacturing route for LiH. In fact, the hydride material is made fromLiCl in two sequential steps: a) electrolysis of the LiCl in the form ofan eutectic system (with, e.g. KCl, Downs-Cell/Process) resulting inLi-metal; followed by step b) the hydrogenation of the Li-metal atelevated temperatures with hydrogen gas (H₂), which results into LiH(schematically):

(Complete Stoichiometry:

2LiCl→2 Li+Cl₂

2Li+H₂→2 LiH).

Other metal hydride sources form by-products which need to beextensively removed (e.g. in case of LiAlH₄→LiCl and AlCl₃) and thuscostly purification steps will interfere with the economy of theprocess. Furthermore, the formation of AlCl₃ is not desired as itspresence induces the redistribution of Me-groups, which will lead to abroadly distributed product mixture (see, e.g. U.S. Pat. No. 5,856,548or 5,654,459A).

The process of the present invention is preferably carried out at atemperature in the range of about −40° C. to about 250° C. Even morepreferably the process of the present invention is carried out at leasttwo different temperatures, preferably at a first temperature which islower than a second temperature. The temperatures are usually selectedin accordance with the requirements of the hydrogenation reaction a),the redistribution reaction b) and the optional cleavage reaction c).

In a preferred embodiment of the process according to the invention, thereactions (hydrogenation reaction, redistribution reaction, and theoptional cleavage reaction) are carried out for more than a total timeof about 4 hours, preferably more than about 6 hours, preferably morethan about 10 hours and preferably more than about 12 hours.

In further preferred embodiment of the process according to theinvention, the reactions (hydrogenation reaction, redistributionreaction, and the optional cleavage reaction) are carried out for morethan a total time of about 4 hours, preferably more than about 6 hoursat a temperature which at least partly exceeds at least about 200° C.,or the reactions in step A) is carried out for more than about 10 hourspreferably more than about 12 hours, at a temperature which at leastpartly exceeds at least about 100° C., preferably more than about 150°C.

The process according to the present invention is preferably carried outat a pressure from about 0.1 to about 10 bar.

The process of the present invention is preferably carried out underinert conditions.

The process of the present invention can be carried out continuously ordiscontinuously, such as batchwise.

In an embodiment, the process of the present invention includes aseparating step to separate the methylchlorohydridosilanes. In apreferred embodiment of the process according to the invention, the stepof separating the methylchlorohydridosilanes is carried out bydistillation and/or condensation.

The term “distillation” according to the present invention relates toany process for separating components or substances from a liquidmixture by selective evaporation and condensation.

Therein, distillation may result in practically complete separation ofthe constituents of a mixture, thus leading to the isolation of nearlypure compounds, or it may be a partial separation that increases theconcentration of selected constituents of the mixture in the distillatewhen compared to the mixture submitted to distillation.

Preferably, the distillation processes can be simple distillation,fractional distillation, vacuum distillation, short path distillation orany other kind of distillation known to the ordinary skilled person.

Also preferably, the step of separating the methylchlorohydridosilanesaccording to the invention can comprise one or more batch distillationsteps, or can comprise a continuous distillation process.

Further preferably, the term “condensation” may comprise separation orenrichment of the methylchlorohydridosilanes from the reaction mixtureby volatilization from the reaction vessel and condensation as a liquidand/or solid in a refrigerated vessel from which it can be subsequentlyrecovered by distillation, or by solution in an ether solvent.

Alternatively preferred, the methylchlorohydridosilanes can be absorbedin an ether solvent contained in a refrigerated vessel.

In a preferred embodiment of the process according to the invention, theprocess is performed under inert conditions.

In accordance with the present invention, the term “performed underinert conditions” means that the process is partially or completelycarried out under the exclusion of surrounding air, in particular ofmoisture and oxygen. In order to exclude ambient air from the reactionmixture and the reaction products, closed reaction vessels, reducedpressure and/or inert gases, in particular nitrogen or argon, orcombinations of such means may be used.

PREFERRED EMBODIMENTS OF THE INVENTION

In the following the preferred embodiments of the invention aresummarized:

-   1. A process for the manufacture of methylchlorohydridomonosilanes,    selected from Me₂Si(H)Cl, MeSi(H)Cl₂, and MeSi(H)₂Cl, preferably    Me₂Si(H)Cl, and MeSi(H)Cl₂, and most preferably Me₂Si(H)Cl,    comprising:    -   subjecting a silane substrate comprising at least one silane        selected from the group consisting of:        -   (i) Monosilanes,        -   (ii) Disilanes,        -   (iii) Oligosilanes,        -   (iv) Carbodisilanes,        -   with the proviso that at least one of the silanes (i)            to (iv) has at least one chloro substituent,    -   a) to a hydrogenation reaction with at least one hydride        donating source, and    -   b) to a redistribution reaction, and    -   c) optionally to a cleavage reaction of the Si—Si bonds of the        di- or oligosilanes or the Si—C-bond of the carbodisilanes, and    -   d) to a separating step of the methylchlorohydridosilanes.    -   wherein the process is carried out in the presence of one or        more solvents, preferably selected from ether solvents, in the        absence of AlCl₃, (also preferably in the absence of a        transition metal compound and even more in the absence of any        metal compound except for the metal compounds used as hydride        donating source, redistribution catalysts, or cleavage catalysts        as described herein), wherein    -   (i) the monosilanes are selected from the general formula (I),

Me_(x)SiH_(y)Cl_(z)  (I),

-   -   -   wherein        -   x=1 to 3,        -   y=0 to 3,        -   z=0 to 3, and        -   x+y+z=4,

    -   (ii) the disilanes are selected from the general empirical        formula (II),

Me_(m)Si₂H_(n)Cl_(o)  (II)

-   -   -   wherein        -   m=1 to 6,        -   n=0 to 5        -   o=0 to 5 and        -   m+n+o=6,

    -   (iii) oligosilanes are selected from linear or branched        oligosilanes of the general empirical formula (III)

Me_(p)Si_(q)H_(r)Cl_(s)  (III),

-   -   -   wherein        -   q=3-7        -   p=q to (2q+2)        -   r, s=0 to (q+2)        -   r+s=(2q+2)−p,

    -   (iv) carbodisilanes are selected from the general formula (IV)

(Me_(a)SiH_(b)Cl_(e))—CH₂-(Me_(c)SiH_(d)Cl_(f))  (IV)

-   -   -   wherein        -   a, c are independently of each other 1 to 3,        -   b, d are independently from each other 0 to 2        -   e, f are independently from each other 0 to 2,        -   a+b+e=3,        -   c+d+f=3.

-   2. A process according to the embodiment 1, wherein the silane    substrate is consisting of the silanes of formulas (I) to (IV). More    preferably the silane substrate is Me₂SiCl₂.

-   3. A process according to any of the previous embodiments, wherein    -   (i) the monosilanes are selected from the formulas:    -   MeSiCl₃, Me₂SiCl₂, Me₃SiCl, MeSiHCl₂, Me₂SiHCl, MeSiH₂Cl,        MeSiH₃, Me₂SiH₂ and Me₃SiH,    -   (ii) the disilanes are selected from the formulas:    -   Cl₂MeSi-SiMeCl₂, Cl₂MeSi-SiMe₂Cl, Cl₂MeSi-SiMe₃ClMe₂Si—SiMe₂Cl,        Me₃Si—SiMe₂Cl, HMe₂Si—SiMe₂Cl,    -   H₂MeSi-SiMeClH, HClMeSi-SiMeClH, ClHMeSi-SiMeCl₂,        H₂MeSi-SiMeCl₂, HMe₂Si—SiMeCl₂, ClMe₂Si—SiMeH₂, HMe₂Si—SiMeClH,        ClMe₂Si—SiMeClH, Me₃Si—SiMeClH, HMe₂Si—SiMe₂H, H₂MeSi-SiMeH₂,        HMe₂Si—SiMeH₂, Me₃Si—SiMeH₂ and Me₃Si—SiMe₂H,    -   (iii) oligosilanes are selected from the formulas:    -   ClMe₂Si—SiMe₂-SiMe₂Cl, ClMe₂Si—SiMe₂-SiMe₂-SiMe₂Cl,        (ClMe₂Si)₃SiMe, (Cl₂MeSi)₂SiMeCl, (Cl₂MeSi)₃SiMe,        (Cl₂MeSi)₂SiMe-SiClMe-SiCl₂Me, [(Cl₂MeSi)₂SiMe]₂,        [(Cl₂MeSi)₂SiMe]₂SiClMe, (Cl₂MeSi)₂SiMe-SiMe₂Cl,        ClMe₂Si—SiMe₂SiMe₂H, HMe₂Si—SiMe₂-SiMe₂H,        HMe₂Si—SiMe₂-SiMe₂-SiMe₂H, (HMe₂Si)₃SiMe, (H₂MeSi)₂SiMeH,        (H₂MeSi)₃SiMe, (H₂MeSi)₂SiMe-SiHMe-SiH₂Me, [(H₂MeSi)₂SiMe]₂,        [(H₂MeSi)₂SiMe]₂SiHMe and (H₂MeSi)₂SiMe-SiMe₂H,    -   (iv) the carbodisilanes are selected from the formulas:    -   Cl₂MeSi—CH₂—SiMeCl₂, ClMe₂Si—CH₂—SiMeCl₂, ClMe₂Si—CH₂—SiMe₂Cl,        Me₃Si—CH₂—SiMeCl₂Me₃Si—CH₂—SiMe₂Cl, HClMeSi—CH₂—SiMeClH,        HMe₂Si—CH₂—SiMeCl₂, HMe₂Si—CH₂—SiMe₂Cl, Me₃Si—CH₂—SiMeClH,        H₂MeSi—CH₂—SiMeH₂, HMe₂Si—CH₂—SiMeH₂, HMe₂Si—CH₂—SiMe₂H,        Me₃Si—CH₂—SiMeH₂, and Me₃Si—CH₂—SiMe₂H    -   with the proviso that at least one of the silanes used in the        process has at least one chloro substituent.

-   4. A process according to any of the previous embodiments, wherein    the silane substrate comprises at least one silane selected from the    group consisting of disilanes (ii), oligosilanes (iii), and    carbodisilanes (iv).

-   5. A process according to any of the previous embodiments, wherein    the silane substrate comprises at least one, preferably more than    one silane selected from the group consisting of MeSiCl₃, Me₂SiCl₂,    Me₃SiCl, MeSiHCl₂, Me₂SiHCl, MeSiH₂Cl, MeSiH₃, Me₂SiH₂, Me₃SiH,    Cl₂MeSi-SiMeCl₂, Cl₂MeSi-SiMe₂Cl, Cl₂MeSi-SiMe₃, ClMe₂Si—SiMe₂Cl,    Me₃Si—SiMe₂C, Cl₂MeSi—CH₂—SiMeCl₂, ClMe₂Si—CH₂—SiMeCl₂,    ClMe₂Si—CH₂—SiMe₂Cl, Me₃Si—CH₂—SiMeCl₂ and Me₃Si—CH₂—SiMe₂Cl.

-   6. A process according to any of the previous embodiments wherein    the process is carried out in the presence of one or more ether    solvents.

-   7. A process according to any of the previous embodiments, wherein    the hydride donating source is selected from metal hydrides,    preferably lithium hydride.

-   8. A process according to any of the previous embodiments, wherein a    cleavage reaction c) of the Si—Si bonds of the di- or oligosilanes    or the Si—C-bond of the carbodisilanes is carried out.

-   9. A process according to any of the previous embodiments, wherein    the redistribution reaction b) is carried out in the presence of at    least one redistribution catalyst.

-   10. A process according to any of the previous embodiments, wherein    the redistribution reaction b) is carried out in the presence of at    least one redistribution catalyst selected from the group consisting    of:    -   R₄PCl, wherein R is hydrogen or an organyl group, which can be        the same or different, more preferably an aromatic group or        aliphatic hydrocarbon group, even more preferably a n-alkyl        group, and most preferably a n-butyl group,    -   triorganophosphines, wherein R is hydrogen or an organyl group,        preferably PPh₃ or n-Bu₃P,    -   triorganoamines, wherein R is an organyl group, preferably        n-Bu₃N or NPh₃,    -   N-heterocyclic amines, preferably non-N-substituted        methylimidazoles, such as 2-methylimidazole, and        4-methylimidazole,    -   quaternary ammonium compounds, preferably n-Bu₄NCl,    -   an alkali metal halide,    -   an alkaline earth metal halide,    -   an alkali metal hydride, and    -   an alkaline earth metal hydride.

-   11. A process according to any of the previous embodiments, wherein    the cleavage reaction c) is carried out in the presence of at least    one cleavage catalyst.

-   12. A process according to any of the previous embodiments, wherein    the cleavage reaction c) is carried out in the presence of at least    one cleavage catalyst selected from the group consisting of:    -   a quaternary Group 15 onium compound R₄QX, wherein each R is        independently a hydrogen or an organyl group, Q is phosphorus,        arsenic, antimony or bismuth, and X is a halide selected from        the group consisting of F, Cl, Br and I,    -   a heterocyclic amine,    -   a heterocyclic ammonium halide,    -   a mixture of R₃P and RX,    -   wherein R is as defined above, and X is as defined above,    -   alkali metal halide,    -   an alkaline earth metal halide,    -   an alkali metal hydride,    -   alkaline earth metal hydride or mixtures thereof,    -   optionally in the presence of hydrogen chloride (HCl).

-   13. A process according to any of the previous embodiments, wherein    the hydrogenation reaction a), the redistribution reaction b), and    optionally the cleavage reaction c) are carried out simultaneously    and/or stepwise, preferably simultaneously.

-   14. A process according to any of the previous embodiments, wherein    the reaction sequence is selected from one or more of the following    process options:    -   the hydrogenation reaction a) and the redistribution reaction b)        are carried out simultaneously, the optional cleavage        reaction c) is carried out subsequently,    -   the hydrogenation reaction a), the redistribution reaction b)        and the cleavage reaction c) are carried out simultaneously,    -   at first the hydrogenation reaction a) is carried out        separately, and then the redistribution reaction b) and        optionally the cleavage reaction c) are carried out        simultaneously or separately, optionally in this embodiment        after the hydrogenation reaction a) the already formed        methylchlorohydridomonosilanes can be separated, before inducing        the redistribution reaction b) and the optional cleavage        reaction c),    -   at first the hydrogenation reaction a) is carried out, then        optionally the cleavage reaction c) is carried out, and then the        redistribution reaction b) is carried out, optionally in this        embodiment after the hydrogenation reaction a) the already        formed methylchlorohydridomonosilanes can be separated, before        inducing the cleavage reaction c) and the redistribution        reaction b),    -   the silane substrate is selected from monosilanes, and such        substrate is subjected first to the hydrogenation reaction a),        and subsequently to the redistribution reaction b), or such        substrate is subjected to the hydrogenation reaction a), and the        redistribution reaction b) simultaneously.

-   15. A process according to any of the previous embodiments, wherein    the methylchlorohydridosilanes are separated after the hydrogenation    step a).

-   16. A process according to any of the previous embodiments, wherein    the silane substrate comprises a product of the Müller-Rochow Direct    Process.

-   17. A process according to any of the previous embodiments, wherein    the silane substrate comprises the entire product of the    Müller-Rochow Direct Process or a part (fraction) of the product of    the Müller-Rochow Direct Process.

-   18. A process according to any of the previous embodiments, wherein    the silane substrate comprises the monosilane fraction of the    Müller-Rochow Direct Process product.

-   19. A process according to any of the previous embodiments, wherein    the silane substrate is the higher silane fraction (silanes having    ≥2 Si atoms) of the Müller-Rochow Direct Process product.

-   20. A process according to any of the previous embodiments, wherein    the silane substrate is the oligosilane fraction (silanes having ≥3    Si atoms) and the carbodisilane fraction of the Müller-Rochow Direct    Process product.

-   21. A process according to any of the previous embodiments, wherein    the silane substrate is the higher silane fraction (silanes having    ≥2 Si atoms) of the Müller-Rochow Direct Process product from which    at least one component has been separated completely or partially,    which component is selected from the group consisting of disilanes    having ≥3 chlorine atoms and disilanes having ≥3 methyl groups.

-   22. A process according to any of the previous embodiments, wherein    the silane substrate comprises a fraction of the Müller-Rochow    Direct Process product, from which at least one component has been    separated completely or partially, which component is selected from    the group consisting of Me_(n)SiCl_(4-n), wherein n=1-3, Me₂Si(H)Cl,    MeSi(H)Cl₂, and MeSi(H)₂Cl.

-   23. A process according to any of the previous embodiments, which    comprises the additional step of separating the monosilanes having    more than one hydrogen atom, and are subjected to a reaction    selected from the group consisting of:    -   a chlorination reaction, preferably with ether/HCl, and/or    -   a redistribution reaction with silanes comprising at least one        chlorine atom.

-   24. A process according to any of the previous embodiments, which    comprises the additional step of separating disilanes and/or    oligosilanes each having at least one hydrogen atom, which are    subjected to a reaction selected from the group consisting of:    -   a cleavage reaction, preferably in the presence ether/HCl,        and/or    -   a redistribution reaction with silanes comprising at least one        chlorine atom.

-   25. A process according to any of the previous embodiments, which    comprises the step of separating carbodisilanes having at least one    hydrogen atom, which are subjected to a reaction selected from the    group consisting of:    -   a cleavage reaction, preferably in the presence of a metal        hydride, and/or    -   a redistribution reaction with silanes comprising at least one        chlorine atom.

-   26. A process according to any of the previous embodiments, which    comprises the step of separating Me₃SiH.

-   27. A process according to any of the previous embodiments, wherein    the hydride donating source is LiH.

-   28. A process according to any of the previous embodiments, wherein    the hydride donating source is LiH, and which process comprises the    step of separating the LiCl formed.

-   29. A process according to any of the previous embodiments, wherein    the hydride donating source is LiH, and which process comprises the    step of separating the LiCl formed and the step of regeneration of    LiH from the separated LiCl.

-   30. A process according to any of the previous embodiments, wherein    the process is carried out at a temperature in the range of about    −40° C. to about 250° C.

-   31. A process according to any of the previous embodiments, wherein    the process is carried out at at least two different temperatures,    preferably at a first temperature which is lower than a second    temperature.

-   32. A process according to any of the previous embodiments, wherein    the process is carried out at a pressure from about 0.1 to about 10    bar.

-   33. A process according to any of the previous embodiments, wherein    the process is carried out under inert conditions.

-   34. A process according to any of the previous embodiments, wherein    the process is carried out continuously or discontinuously, such as    batchwise.

-   35. Methylchlorohydridomonosilanes, selected from Me₂Si(H)Cl,    MeSi(H)Cl₂, and MeSi(H)₂Cl, as obtainable by the process according    to any of the previous embodiments.

-   36. Compositions, comprising at least one    methylchlorohydridomonosilane, selected from Me₂Si(H)Cl, MeSi(H)Cl₂,    and MeSi(H)₂Cl, as obtainable by the process according to any of the    previous embodiments.

It will be understood that any numerical range recited herein includesall sub-ranges within that range and any combination of the variousendpoints of such ranges or sub-ranges, be it described in the examplesor anywhere else in the specification.

It will also be understood herein that any of the components of theinvention herein as they are described by any specific genus or speciesdetailed in the examples section of the specification, can be used inone embodiment to define an alternative respective definition of anyendpoint of a range elsewhere described in the specification with regardto that component, and can thus, in one non-limiting embodiment, be usedto supplant such a range endpoint, elsewhere described.

It will be further understood that any compound, material or substancewhich is expressly or implicitly disclosed in the specification and/orrecited in a claim as belonging to a group of structurally,compositionally and/or functionally related compounds, materials orsubstances includes individual representatives of the group and allcombinations thereof.

While the above description contains many specifics, these specificsshould not be construed as limitations on the scope of the invention,but merely as exemplifications of preferred embodiments thereof. Thoseskilled in the art may envision many other possible variations that arewithin the scope and spirit of the invention as defined by the claimsappended hereto.

The process of the present invention will be explained in more detail bythe following examples.

EXAMPLES

The present invention is further illustrated by the following examples,without being limited thereto.

General

Various silane substrates as formed in the Direct Process of formationof methylchlorosilanes were reacted. All reactants and solvents usedwere carefully dried according to procedures known from literature. Thereactions investigated were generally performed in sealed NMR tubesfirst to prevent evaporation of low boiling reaction products, and toelucidate the reaction conditions (temperature, time) forsilicon-silicon bond cleavage. Subsequently, these conditions wereexemplarily transferred to a preparative scale: (i) in a closed system,preferably a sealed glass ampoule to avoid evaporation of low boilingreaction educts and products, e.g. organo chloro- and organohydridosilanes. After the reactions were completed, the ampoule wasfrozen opened under vacuum and products formed were isolated by combinedcondensation/disitillation procedures. (ii) in an open system,preferably a multi-necked flask, equipped with a magnetic stirrer,thermometer, dropping funnel, and a reflux condenser that was connectedwith a cooling trap to collect low boiling reaction products. Productsformed were isolated by combined condensation/distillation procedures.Products were analyzed and characterized by standard procedures,especially by NMR spectroscopy and GC/MS analyses.

Identification of Products

Products were analyzed by ¹H, ²⁹Si and ¹H-²⁹Si-HSQC NMR spectroscopy.The spectra were recorded on a Bruker AV-500 spectrometer equipped witha Prodigy BBO 500 S1 probe. ¹H-NMR spectra were calibrated to theresidual solvent proton resonance ([D₆]benzene δ_(H)=7.16 ppm). Productidentification was additionally supported by GC-MS analyses and verifiedidentification of the main products. GC-MS analyses were measured with aThermo Scientific Trace GC Ultra coupled with an ITQ 900MS massspectrometer. The stationary phase (Machery-Nagel PERMABOND Silane) hada length of 50 m with an inner diameter of 0.32 mm. 1 μl of analytesolution was injected, 1/25 thereof was transferred onto the column witha flow rate of 1.7 mL/min carried by helium gas. The temperature of thecolumn was first kept at 50° C. for 10 minutes. Temperature was thenelevated at a rate of 20° C./min up to 250° C. and held at thattemperature for another 40 minutes. After exiting the column, substanceswere ionized with 70 eV and cationic fragments were measured within arange of 34-600 m/z (mass per charge). Product mixtures were dilutedwith benzene prior to the measurement.

The characteristic ²⁹Si-NMR chemical shifts and coupling constants¹J{²⁹Si-¹H} for the starting materials reacted with the alkali- andalkaline earth metal salts and the products formed, are listed in Table1.

TABLE 1 Identification of starting materials and products Compound δ²⁹Si [ppm] ¹J (Si—H) [Hz] No. Si^(A)—Si^(B) A B A B 1 Cl₂MeSi—SiMeCl₂17.5 — 2 ClMe₂Si—SiMeCl₂ 15.0 24.6 — 3 ClMe₂Si—SiMe₂Cl 17.1 — 4Me₃Si—SiMeCl₂ 34.0 −14.1 — 5 Me₃Si—SiMe₂Cl 22.5 −18.6 — 6 Me₃Si—SiMe₃−20.1 — 7 MeSiCl₃ 12.3 — 8 MeSiHCl₂ 10.9 280.2 9 MeSiH₂Cl −11.4 229.4 10MeSiH₃ −65.5 194.1 11 Me₂SiCl₂ 31.5 — 12 Me₂SiHCl 11.0 223.3 13 Me₂SiH₂−38.1 187.6 14 Me₃SiCl 30.1 — 15 Me₃SiH −16.6 182.9 16 H₂MeSi—SiMeH₂−67.8 185.8 17 HMe₂Si—SiMeH₂ −39.9 −66.7 180.9 180.5 18 HMe₂Si—SiMe₂H−39.5 177.5 19 Me₃Si—SiMeH₂ −18.3 −66.0 — 177.7 20 Me₃Si—SiMe₂H −19.2−39.4 — 172.5 21 ClMe₂Si—SiMe₂H 23.0 −39.0 — 176.4 22 Cl₂MeSi—SiMeClH23.8 −6.7 — 227.4 23 HClMeSi—SiMeClH −3.9 −4.3 211.7 24 Cl₂MeSi—SiMeH₂32.1 −61.4 — 196.7 25 HClMeSi—SiMeH₂ 0.6 −64.7 215.0 203.3 26ClMe₂Si—SiMeClH 17.6 −3.7 — 221.3 27 Cl₂MeSi—SiMe₂H 33.8 −35.5 — 191.328 ClMe₂Si—SiMeH₂ 22.6 −64.6 — 195.6 29 HMe₂Si—SiMeClH 1.83 −38.2 181.3198.4 30 Cl₂MeSi—CH₂—SiMeCl₂ 26.2 — 31 ClMe₂Si—CH₂—SiMeCl₂ 28.1 25.7 — —32 ClMe₂Si—CH₂—SiMe₂Cl 28.3 — 33 Me₃Si—CH₂—SiMeCl₂ 30.6 −0.5 — — 34Me₃Si—CH₂—SiMe₂Cl 30.0 −0.4 — — 35 Me₃Si—CH₂—SiMe₃ −0.5 —

Example 1

LiH (3.0 mmol), Me₂SiCl₂ (1.7 mmol), tetraglyme (0.35 ml) and catalyticamounts of n-Bu₄PCl (0.02 mmol) were placed in an NMR tube cooled to−196° C. (liquid nitrogen). After evacuation the NMR tube was sealed andwarmed to r.t. The starting materials reacted upon heating the sample,and the reaction course of the chlorosilane reduction/redistributionreaction was monitored by NMR spectroscopy.

TABLE 2 80° C., 120° C., 120° C., 120° C., no. silane 0.25 h +2 h +2.5 h+6 h 13 Me₂SiH₂ 31 35 47 55 11 Me₂SiCl₂ 57 20 7 3 12 Me₂SiHCl 12 45 4642

As can be seen from Table 2, the formation of hydridosilane (13) wassteadily increasing with increasing reaction temperature and time. Themaximum molar amount (in %) of chlorosilane 12 (Me₂Si(H)Cl) essentiallyformed by redistribution of hydridosilane (13) with dichlorosilane 11 isabout 46%. At 120° C./10 h the molar amount of Me₂SiCl₂ was reduced toonly 3% yield, thus being hardly available for further redistributionwith Me₂SiH₂, present in 55 mol-% under these reaction conditions. Asmentioned above Me₂SiH₂ can be in turn subjected to a chlorinationreaction preferably with ether/HCl or a redistribution reaction withsilanes comprising at least one chlorine atom, for which theredistribution catalysts can be used as described above.

Example 2

The reaction was performed in an analogous manner to the reaction ofExample 1 except for using diglyme as solvent.

Table 3 covers the experimental findings of running the reaction asdescribed. The yield of the target compound 12 was 55% at 120° C./+2 h.

TABLE 3 80° C., 120° C., 120° C., 120° C., no. silane 0.25 h +2 h +2.5 h+6 h 13 Me₂SiH₂ 37 24 36 45 11 Me₂SiCl₂ 51 21 13 5 12 Me₂SiHCl 12 55 5150

Example 3

In analogy to the reaction of Example 1, MeSiCl₃ (1.7 mmol), tetraglyme(0.35 ml) and catalytic amounts of n-Bu₄PCl (0.02 mmol) were placed inan NMR tube, cooled to −196° C. (liquid nitrogen), then LiH (2.5 mmol)was added; the NMR tube was evacuated, sealed and warmed to r.t. Thestarting materials reacted upon heating the sample, and the course ofthe chlorosilane reduction/redistribution reaction was monitored by NMRspectroscopy.

TABLE 4 80° C., 120° C., 120° C., 120° C., 120° C., no. silane 0.25 h +2h +2.5 h +6 h +60 h 7 MeSiCl₃ 55 33 12 8 3 8 MeSiH₂Cl — — 14 23 32 9MeSiHCl₂ 45 67 74 67 60 10 MeSiH₃ — — — 2 5

As listed in Table 4, the molar amount of methyltrichlorosilane (7) wassteadily decreasing with increasing reaction temperatures and reactiontimes, and the amount of the target compound MeSiHCl₂ (9) increased to74%, while MeSiH₂Cl (8) was formed in 14% yield at 120° C. (+4.5 h).With prolonged reaction times, chlorosilane 7 was reduced almostquantitatively. With prolonged reaction times at 120° C., the amount of9 decreased (60%) due to excess LiH, that supported formation ofhydridochlorosilanes 8 (32%) and hydridosilane 10 (5%).

Example 4

The reaction was performed in analogy to the reaction of Example 3, butusing diglyme as solvent and 2.7 mmol LiH. Table 5 covers the results ofrunning the reaction as described, showing comparable trends and givingsimilar results as obtained in Example 3. Notably, already with shortreaction time, overall hydrogenation is about 90%. The equilibriumbetween silanes 8 and 9 was shifted with prolonged reaction times,implying targeted product formation by simply controlling the reactionconditions.

TABLE 5 80° C./0.25 120° C., 120° C., 120° C., no. silane h + 120° C./2h +2.5 h +6 h +60 h 7 MeSiCl₃ 9 5 3 2 8 MeSiH₂Cl 23 28 37 41 9 MeSiHCl₂66 63 53 48 10 MeSiH₃ 2 3 7 9

Example 5

LiH (1.5 mmol), Me₂SiCl₂ (1.6 mmol), diglyme (0.4 ml) and a catalyticamount of n-Bu₄NCl (0.02 mmol) were placed in an NMR tube that wascooled to −196° C. (liquid nitrogen). After evacuation in vacuo the NMRtube was sealed and warmed to r.t. The starting materials reacted uponheating the sample, and the reaction course of the chlorosilanereduction/redistribution reaction was monitored by NMR spectroscopy.

TABLE 6 120° C., 160° C., no. silane 22 h +40 h 13 Me₂SiH₂ 7 10 11Me₂SiCl₂ 42 41 12 Me₂SiHCl 52 49

After 22 h at 120° C. dimethyldichlorosilane was hydrogenated to givedimethylsilane 13 that subsequently redistributed withdimethyldichlorosilane 11 to give Me₂SiHCl (12) in 52% yield. Increasingthe reaction temperature and time led to further hydrogenation ofchlorosilanes but did not change the product distribution significantly(Table 6).

Example 6

The reaction was performed in an analogous manner to the reaction ofExample 5 except for using PPh₃ (0.02 mmol) as a redistributioncatalyst.

TABLE 7 120° C., 160° C., 160° C., no. silane 13 h +22 h +40 h 13Me₂SiH₂ 32 14 11 11 Me₂SiCl₂ 66 47 33 12 Me₂SiHCl 2 39 56

As can be seen from Table 7, the formation of Me₂SiHCl (12) was steadilyincreasing with increasing reaction temperature and time. The maximumamount of chlorosilane 12 essentially formed by redistribution ofhydridosilane 13 with dichlorosilane 11 was 56% after 62 h at 160° C.

Example 7

The reaction was performed in analogy to the reaction of Example 5,except for using n-Bu₃P (0.02 mmol) as redistribution catalyst.

TABLE 8 120° C., 160° C., 160° C., no. silane 13 h +22 h +40 h 13Me₂SiH₂ 34 25 16 11 Me₂SiCl₂ 64 48 30 12 Me₂SiHCl 2 27 54

Similar to Example 6, the maximum amount of chlorosilane 12 formed byredistribution was 54% after 62 h at 160° C. (Table 8).

Example 8

The reaction was performed in an analogous manner to the reaction ofExample 5 except for using 2-methylimidazole (0.02 mmol) asredistribution catalyst.

TABLE 9 120° C., 160° C., 200° C., no. silane 13 h +22 h +40 h 13Me₂SiH₂ 34 39 21 11 Me₂SiCl₂ 65 57 24 12 Me₂SiHCl 1 4 52 not ident. — 3

In contrast to Example 6 and 7, Me₂SiHCl (12) was formed only in a molaramount of 4% after 22 h/160° C. Increasing the reaction temperature andtime to 200° C./40 h finally gave 12 in 52% yield (Table 9).

Example 9

Me₂SiCl₂ (0.8 mmol), Me₂ClSi—SiClMe₂ (0.8 mmol), LiH (2.5 mmol), diglyme(0.4 ml) and catalytic amounts of n-Bu₄PCl (0.04 mmol) were placed in anNMR tube cooled to −196° C. (liquid nitrogen). After evacuation the NMRtube was sealed, warmed and the reaction course was investigated NMRspectroscopically.

TABLE 10 120° C., 120° C., no. silane 13 h +22 h 13 Me₂SiH₂ 17 35 11Me₂SiCl₂ 9 6 12 Me₂SiHCl 44 42 3 (Me₂ClSi)₂ 9 1 18 (Me₂HSi)₂ 4 6 21Me₂ClSi—SiHMe₂ 17 5 trisilanes — 5

At 120° C./13 h Me₂ClSi—SiClMe₂ was cleaved as well as partially andfully hydrogenated to give compound 18 in 4% and compound 21 in 17%yield. Targeted product Me₂SiHCl (12) was formed in 44% besides Me₂SiH₂(13) in 17% yield. Prolonged reaction times (+22 h) led to furtherhydrogenation by LiH to give hydridosilane 13 in a molar amount of 35%,while targeted product 12 was reduced to 42%. The amount of disilanes 3and 21 decreased to 1% and 5% yield, respectively, while the molaramount of the fully hydrogenated disilane 18 increased slightly (6%).Trisilanes were formed in 5% (Table 10).

Example 10

MeCl₂Si—SiCl₂Me (0.6 mmol), MeSiCl₃ (0.6 mmol), LiH (1.5 mmol), diglyme(0.4 ml) and PPh₃ (0.05 mmol) as redistribution catalyst were placed inan NMR tube cooled to −196° C. (liquid nitrogen). After evacuation theNMR tube was sealed, warmed and the reaction course was investigated NMRspectroscopically.

TABLE 11 160° C., 220° C., no. silane 16 h +15 h 7 MeSiCl₃ 42 29 8MeSiH₂Cl 8 11 9 MeSiHCl₂ 50 56 not ident. — 4

After 16 h at 160° C. the starting disilane MeCl₂Si—SiCl₂Me (1) wasquantitatively cleaved and via redistribution reactions the targetedproducts MeSiHCl₂ (8) and MeSiH₂Cl (9) were formed in 50% and 8% yield,respectively. With prolonged reaction times (+15 h) at 220° C. the molaramounts of compounds 8 and 9 were further increased to 56% and 11%,while not identified products were formed in a molar amount of 4% (Table11).

Example 11

0.6 mmol of a complex mixture of chlorocarbodisilanes (carbodisilanedistribution is listed in Table 12), Me₂SiCl₂ (0.8 mmol), LiH (1.6mmol), n-Bu₃P (0.05 mmol) and diglyme (0.3 ml) were placed in a cooledNMR tube (−196° C.). After evacuation in vacuo the NMR tube was sealedand warmed to r.t. The starting materials reacted upon heating thesample, and the reaction course of the chlorosilanereduction/redistribution reaction was monitored by NMR spectroscopy.

TABLE 12 no. silane educt (%) 30 (Cl₂MeSi)₂—CH₂ 45 31ClMe₂Si—CH₂—SiMeCl₂ 31 32 (Me₂ClSi)₂—CH₂ 14 34 Me₃Si—CH₂—SiMe₂Cl 10

TABLE 13 160° C., 220° C., no. silane 16 h +15 h 13 Me₂SiH₂ 34 5 11Me₂SiCl₂ 36 25 12 Me₂SiHCl 8 34 9 MeSiH₂Cl — 7 8 MeSiHCl₂ — 7 10 MeSiH₃2 9 carbodisilanes 20 13

After 16 h at 160° C. the targeted product Me₂SiHCl (12) as well asdimethylsilane were formed in 8% and 34% yield, respectively.Hydrogenation and cleavage of chlorocarbodisilanes gave methylsilane 10in 2% yield. With prolonged reaction times (+15 h) at 220° C. the molaramount of 12 increased to 34%, while that of Me₂SiH₂ (13) decreased (5%)due to redistribution reactions with chlorosilanes. Carbodisilanes werefurther cleaved (13% remained) to give silanes 8, 9 and 10 in 7%, 7% and9% yield, respectively (Table 13).

Example 12

MeSiCl₃ (1.7 mmol) and tetraglyme (0.35 ml) were placed in an NMR tube,cooled to −196° C. (liquid nitrogen), then LiH (2.5 mmol) was added; theNMR tube was evacuated, sealed and warmed to r.t. The starting materialsreacted upon heating the sample, and the course of the chlorosilanereduction/redistribution reaction was monitored by NMR spectroscopy. Aslisted in Table 14, the target compounds MeSiHCl₂ (8, 11%) and MeSiH₂Cl(9, 28%) were formed at 160° C., but required longer reaction times.

TABLE 14 60° C., 100° C., 120° C., 160° C., no. silane 2 min +19 h +40 h+40 h 7 MeSiCl₃ 75 60 54 36 9 MeSiH₂Cl 2 6 10 28 8 MeSiHCl₂ 1 4 5 11 10MeSiH₃ 22 30 31 25

Example 13

Example for the Subsequent Treatment of Perhydrated by-Products, Such asMe₂SiH₂, by Chlorination with HCl in Ether Solvents

Upon warming Me₂SiH₂ to r.t. it was evaporated into a 1 L flask filledwith the HCl/diglyme reagent (170 g, 4.7 mol of HCl in 540 ml diglyme)that was cooled to −45° C. After completion (1.5 h) the reaction mixturewas stirred for 4 h and then allowed to warm to 15° C. over a period of8 hours. The HCl/diglyme flask was connected with a cooling trap (−78°C.) and after the overall reaction time of 12 hours a mixture of 16.85 g(0.28 mol) Me₂SiH₂, 0.83 g (9 mmol) Me₂SiHCl and 0.13 g (3 mmol) ofmethyl chloride were collected. Volatile compounds of the HCl/diglymesolution were condensed under vacuum in a cooling trap (about −196° C.)that was connected to another trap cooled to about −78° C. The condensedmixture (about −196° C.) was allowed to warm to r.t. at normal pressure(about 1013 mbar) separating dimethylchlorosilane formed from gaseoushydrogen chloride: Me₂SiHCl was collected in the −78° C. cooling trapwhile excess HCl was directly recycled by evaporation into a 1 L flaskfilled with diglyme used for the chlorination reaction at the beginning.The Me₂SiHCl collected in the −78° C. trap was condensed into an ampoulewith Young-valve to give 59 g (0.62 mol) of Me₂SiHCl besides traces ofmethyl chloride and Me₂SiCl₂, obviously formed by double chlorination ofMe₂SiH₂.

Me₂SiH₂, collected in the −78° C. cooling trap after chlorinationreaction (16.85 g, see above), was additionally evaporated into the(recycled) HCl/diglyme mixture and reacted and worked up as describedbefore, giving 25 g (0.27 mol) Me₂SiHCl, contaminated with traces ofmethyl chloride. Combining both Me₂SiHCl fractions and finaldistillation over a 50 cm Vigreux column at normal pressure gave 74 g(0.89 mol) of Me₂SiHCl (b.p.: 35° C.), in a yield of 99% for thechlorination step.

Example 14

A mixture of 112 mg highly chlorinated disilanes 69 mol %Cl₂MeSi-SiMeCl₂, 26 mol % ClMe₂Si—SiMeCl₂, 4 mol % ClMe₂Si—SiMe₂Cl and 1mol % Me₃Si—SiMeCl₂ were reacted with 8.1 mg LiH (50 mol %, in relationto chlorine content in the mixture) in diglyme as solvent. Reduction,redistribution and cleavage of chloro-mono- and disilanes started atr.t. as indicated by warming up of the reaction mixture. The productsformed are listed in Table 15. The cleavage of disilanes was nearlyquantitative, only highly methylated disilane ClMe₂Si—SiMe₂Cl remainedin traces (˜1%). Monosilane MeSiH₂Cl is the main product followed bymonosilane 8.

TABLE 15 no. silane mol % 8 MeSiHCl₂ 21 12 Me₂SiHCl 9 9 MeSiH₂Cl 33 11Me₂SiCl₂ 19 14 Me₃SiCl 2 7 MeSiCl₃ 2 10 MeSiH₃ 13 3 ClMe₂Si—SiMe₂Cl 1

Example 15

Reaction of the methylchlorodisilane mixture (183 mg) of the sample fromExample 14 with LiH in diglyme can easily be controlled by the amount ofLiH reacted. Reduction of LiH to 41 mol % (10 mg, in relation tochlorine content in the mixture (when compared to Example 14) avoidsformation of the low boiling monosilane MeSiH₃, instead dichlorsilanesMeSiHCl₂ and Me₂SiCl₂ became the main products. The overall productcomposition is listed in Table 16, about 2 mol % disilanes remainedunreacted. The reaction occurred at r.t. under self-heating of thesample to about 40° C.

TABLE 16 no. silane mol % 8 MeSiHCl₂ 37 12 Me₂SiHCl 7 9 MeSiH₂Cl 6 11Me₂SiCl₂ 34 14 Me₃SiCl 2 7 MeSiCl₃ 11 1 Cl₂MeSi—SiMeCl₂ 0.5 3ClMe₂Si—SiMe₂Cl 1.5

Example 16

The results of Example 15 are further investigated by treating themixture of disilanes (110 mg-159 mg) of Example 14 with different molaramounts of LiH (25 mol-%, 50 mol-%, 75 mol-%, 100 mol-% and 400 mol-%,in relation to chlorine content in the mixture) in diglyme. Allreactions occurred at r.t. with self-heating of the samples. Theproducts formed are listed in Table 17 and demonstrate that aftercleavage of the silicon-silicon bonds the resulting chlorinatedmonosilanes are further transformed into hydrogen-substitutedmonosilanes by LiH.

The higher the chloro substitution at Si is, the faster hydrogenationoccurs: MeSiCl₃>Me₂SiCl₂>Me₃SiCl. The same is true for the onlypartially hydrated monosilanes MeH₂SiCl>MeSiHCl₂>Me₂SiHCl. Especiallythe latter reacts very slowly because the molar amount of thischlorosilane remains nearly constant in all reactions performed. Withhigh excess of LiH (about 400 mol %) all chloro substituted monosilanesare completely reacted to the per hydrogenated silanes Me₂SiH₂ (6%)MeSiH₃ (78%) and the per hydrogenated disilanes

H₂MeSi-SiMeH₂, HMe₂Si—SiMeH₂,

HMe₂Si—SiMe₂H and Me₃Si—SiMeH₂.

The results of this series of experiments are listed in the Table 17. Insummary, for the synthesis of monohydrated silanes such as MeSiHCl₂ andMe₂SiHCl, LiH should be used in stoichiometric deficit (<about 25 mol%), for an increase of the amount of monosilane MeSiH₂Cl the molaramount of LiH is best about 25 mol-% to about 75 mol %. For a completeformation of perhydrido-methylsilanes (MeSiH₃ and Me₂SiH₂) LiH should beused in excess, but this is not desirable according to the presentinvention.

TABLE 17 LiH conc. [ mol %] 25 50 75 100 400 no. silane mol % mol % mol% mol % mol % 8 MeSiHCl₂ 30 21 6 2 — 12 Me₂SiHCl 11 13 12 12 — 9MeSiH₂Cl 18 35 30 24 — 13 Me₂SiH₂ — — 2 3 6 10 MeSiH₃ 7 13 41 56 78  11Me₂SiCl₂ 21 15 7 2 — 14 Me₃SiCl 2 2 1 traces — 3 ClMe₂Si—SiMe₂Cl 1 1 1 1— 16 H₂MeSi—SiMeH₂ — — — traces 8 17 H₂MeSi—SiMe₂H — — — — 5 19Me₃Si—SiMeH₂ — — — — 2 18 HMe₂Si—SiMe₂H — — — — 1

Example 17

The reaction of a complex mixture (131-238 mg) of mainly highlychlorinated disilanes and monosilanes as displayed in Table 18 wasreacted with 41 mol % or 73 mol % LiH (in relation to chlorine contentin the mixture), respectively, in diglyme at r.t. with self-heating. Theproducts formed are listed in Table 19 and show that monosilanes areformed in a molar amount of 96%, and 4 mol % of tetramethyldichloro- andpentamethylchlorodisilane remained unreacted. Higher amounts of LiH leadto increasing amounts of hydrogen substituted silanes by Si—Cl→Si—Hreduction.

TABLE 18 no. silane mol % 11 Me₂SiCl₂ 7.9 5 Me₃Si—SiMe₂Cl 2.0 3ClMe₂Si—SiMe₂Cl 3.5 1 Cl₂MeSi—SiMeCl₂ 49.5 2 ClMe₂Si—SiMeCl₂ 33.7 4Me₃Si—SiMeCl₂ 3.0 6 Me₃Si—SiMe₃ 0.4

TABLE 19 LiH conc. [mol %] 41 73 no. silane mol % mol % 8 MeSiHCl₂ 17 1112 Me₂SiHCl 14 21 9 MeSiH₂Cl 20 26 13 Me₂SiH₂ — 2 10 MeSiH₃ 6 16 11Me₂SiCl₂ 35 16 14 Me₃SiCl 4 4 3 ClMe₂Si—SiMe₂Cl 2 2 5 Me₃Si—SiMe₂Cl 2 26 Me₃Si—SiMe₃ traces traces

Example 18

For hydrogenation of methylchlorodisilanes tributyltin hydride was usedas reducing agent. For the preparation of n-Bu₃SnH see: U. Herzog, G.Roewer and U. Pitzold, Katalytische Hydrierung chlorhaltiger Disilanemit Tributylstannan, J. Organomet. Chem 1995, 494, 143-147.

Disilane (ClMe₂Si—SiMe₂Cl, admixed with 5 mol % Me₃Si—SiMe₂Cl) (4.04 g)was reacted in a 1/1 molar ratio with the tin hydride in diglyme andtetraphenylphosphoniumchloride (Ph₄PCl, 3 w %) as catalyst at r.t. Afterwork up, a mixture of the disilanes ClMe₂Si—SiMe₂Cl (15 mol %),Me₃Si—SiMe₂Cl (4 mol %), ClMe₂Si—SiMe₂H (72 mol %) and Me₃Si—SiMe₂H (9mol %) was obtained. 200 mg of those disilanes were subsequently reactedwith tetrabutylphosphoniumchloride (n-Bu₄PCl, 25 w %) in a sealed NMRtube at 180° C. for 9 h. As listed in Table 20, the hydrido disilaneClMe₂Si—SiMe₂H was nearly completely cleaved into the monosilanesMe₂SiHCl and Me₂SiH₂ that were formed in 68 mol % yield. ChlorosilaneMe₃SiCl results from cleavage of the disilane Me₃Si—SiMe₂Cl.Unidentified oligosilanes were detected in small amounts.

TABLE 20 no. silane mol % 12 Me₂SiHCl 37 13 Me₂SiH₂ 31 14 Me₃SiCl 14 11Me₂SiCl₂ 8 15 Me₃SiH 1 educts, oligosilanes 9

The mixture of disilanes ClMe₂Si—SiMe₂Cl (15 mol %), Me₃Si—SiMe₂Cl (4mol %), ClMe₂Si—SiMe₂H (72 mol %) and Me₃Si—SiMe₂H (9 mol %) as obtainedabove from hydrogenation (200 mg) was reacted with 2-methylimidazole(2-MIA, 16 w %) in a sealed NMR tube at 220° C. for 9 h. The amount ofchlorosilane Me₂SiHCl was smaller than in the reaction in the presenceof tetrabutylphosphoniumchloride, the main product obtained wasdimethylsilane Me₂SiH₂, followed by Me₃SiCl (13.2 mol %). Remainingdisilanes Me₃Si—SiMe₂Cl and Me₃Si—SiMe₂H were 15.0 mol % respectively8.2 mol %. Notably, perhydrogenated disilane HMe₂Si—SiMe₂H was detectedin 1.0 mol % (Table 21).

Prolonged reaction times (69 h) lead to almost quantitative splitting ofH-substituted disilanes as well as conversion of tri- and tetrasilanes(ClMe₂Si—SiMe₂-SiMe₂Cl and ClMe₂Si—SiMe₂-SiMe₂-SiMe₂Cl), named in thetable as “oligosilanes”, into monomers. Products obtained are listed inTable 22 and prove formation of Me₂SiHCl (˜40 mol %) as main component.

TABLE 21 no. silane mol % 12 Me₂SiHCl 17.1 13 Me₂SiH₂ 31.5 14 Me₃SiCl13.2 11 Me₂SiCl₂ 8.8 21 ClMe₂Si—SiMe₂H 15.0 20 Me₃Si—SiMe₂H 8.2 18HMe₂Si—SiMe₂H 1.0 oligosilanes 5.2

TABLE 22 no. silane mol % 12 Me₂SiHCl 39.5 13 Me₂SiH₂ 34.0 14 Me₃SiCl13.4 11 Me₂SiCl₂ 7.3 21 ClMe₂Si—SiMe₂H 5.8

Example 19

Hydrogenation Reaction

For simulation of a mono- and disilane fraction obtained from theMüller-Rochow-Direct Process, a mixture (1.10 g) of compounds listed inTable 24, (1.19 g) of monosilane Me₂SiCl₂ and highly chlorinateddisilanes listed in Table 25 and (1.07 g) of compounds listed in Table23 were mixed and reacted with different molar amounts of n-Bu₃SnH toreplace 25, 50 and 75 mol % of all chlorine substituents at silicon.After reduction, the products were isolated by condensation/distillationto give the product mixtures IV, V and VI listed in Table 26.

TABLE 23 no. silane mol % 11 Me₂SiCl₂ 12.4 14 Me₃SiCl 2.2 7 MeSiCl₃ 11.55 Me₃Si—SiMe₂Cl 16.8 3 ClMe₂Si—SiMe₂Cl 22.6 1 Cl₂MeSi—SiMeCl₂ 16.2 2ClMe₂Si—SiMeCl₂ 7.1 4 Me₃Si—SiMeCl₂ 2.7 6 Me₆Si2 2.4 34Me₃Si—CH₂—SiMe₂Cl 3.1 30 (Cl₂MeSi)₂—CH₂ 0.4 31 ClMe₂Si—CH₂—SiMeCl₂ 0.933 Me₃Si—CH₂—SiMeCl₂ 0.4 35 Me₃Si—CH₂—SiMe₃ 1.3

TABLE 24 no. silane mol % 11 Me₂SiCl₂ 6.8 14 Me₃SiCl 7.1 7 MeSiCl₃ 12.512 Me₂SiHCl 4.3 8 MeSiHCl₂ 1.4 5 Me₃Si—SiMe₂Cl 3.9 3 (ClMe₂Si)₂ 17.9 1(Cl₂MeSi)₂ 1.4 6 Me₆Si₂ 0.2 34 Me₃Si—CH₂—SiMe₂Cl 3.9 32 (ClMe₂Si)₂—CH₂5.2 30 (Cl₂MeSi)₂—CH₂ 14.7 31 ClMe₂Si—CH₂—SiMeCl₂ 11.4 33Me₃Si—CH₂—SiMeCl₂ 1.8 35 Me₃Si—CH₂—SiMe₃ 7.5

TABLE 25 no. silane mol % 11 Me₂SiCl₂ 7.9 5 Me₃Si—SiMe₂Cl 2.0 3ClMe₂Si—SiMe₂Cl 3.5 1 Cl₂MeSi—SiMeCl₂ 49.5 2 ClMe₂Si—SiMeCl₂ 33.7 4Me₃Si—SiMeCl₂ 3.0 6 Me₃Si—SiMe₃ 0.4

TABLE 26 sample IV sample V sample VI no. silane mol % mol % mol % 3ClMe₂Si—SiMe₂Cl 18 9 7 11 Me₂SiCl₂ 18 20  27  5 Me₅Si₂Cl 16 23  28  7MeSiCl₃ 13 7 9 16 H₂MeSi—SiMeH₂ 9 18  — 2 ClMe₂Si—SiMeCl₂ 4 — — 33Cl₂MeSi—CH₂—SiMe₃ 4 2 3 9 MeSiH₂Cl 3 — — 24 H₂MeSi—SiMeCl₂ 3 3 1 17HMe₂Si—SiMeH₂ 3 2 1 6 Me₃Si—SiMe₃ 2 5 4 31 ClMe₂Si—CH₂—SiMeCl₂ 2 2 6 4Me₃Si—SiMeCl₂ 1 2 4 18 HMe₂Si—SiMe₂H 1 1 2 30 Cl₂MeSi—CH₂—SiMeCl₂ 1 3 231 ClMe₂Si—CH₂—SiMe₂Cl 1 2 4 34 ClMe₂Si—CH₂—SiMe₃ 1 1 3

Redistribution and Cleavage Reaction

Redistribution and cleavage reactions with the mixture of sample IV oftable 26 (280 mg) were performed with n-Bu₄PCl (6 w %) in a sealed NMRtube. NMR measurements were taken at r.t., 140° C. (+23 h) and 220° C.(+16 h). Cleavage reactions already started at r.t. and only traces ofMe₃Si—SiMe₃ (˜1 mol %) remained unreacted at 220° C. (Table 27).

TABLE 27 r.t./1 h 140° C./+23 h 220° C./+16 h no. silane mol % mol % mol% 3 ClMe₂Si—SiMe₂Cl 12.1 — 12 Me₂SiHCl 16.5 20.8 21.6 14 Me₃SiCl 1.1 5.011.3 11 Me₂SiCl₂ 10.1 37.5 40.2 7 MeSiCl₃ — — — 8 MeSiHCl₂ 16.7 10.2 7.49 MeSiH₂Cl 14.4 11.1 11.3 13 Me₂SiH₂ — — 1.9 10 MeSiH₃ 8.8 5.6 2.7 6Me₃Si—SiMe₃ 0.9 0.6 1.1 5 Me₃Si—SiMe₂Cl 7.5 2.8 — carbodisilanes 11.96.4 2.5

In Table 28 the results of the comparable cleavage and redistributionreactions of samples V and VI are listed.

TABLE 28 sample V sample VI r.t. 140° C. 220° C. r.t. 140° C. 220° C. 1h +23 h +16 h 1 h +23 h +16 h no. silane mol % mol % mol % mol % mol %mol % 3 ClMe₂Si—SiMe₂Cl 13.1 — — 18.1 — — 12 Me₂SiHCl 18.6 36.4 29.714.3 29.5 27.3 14 Me₃SiCl 1.6 11.3 17.4 2.6 13.6 22.9 11 Me₂SiCl₂ 11.328.9 29.2 15.4 37.8 37.2 8 MeSiHCl₂ 6.2 1.5 2.0 1.1 0.8 1.2 9 MeSiH₂Cl6.3 1.6 4.3 0.7 — 2.7 13 Me₂SiH₂ 1.1 2.5 7.2 2.5 1.5 2.3 10 MeSiH₃ 11.45.4 6.9 5.2 2.3 1.7 6 Me₃Si—SiMe₃ 1.3 2.0 1.2 2.0 2.6 1.3 5Me₃Si—SiMe₂Cl 16.9 2.4 — 19.7 1.5 — carbodisilanes 12.2 8.0 2.1 18.410.4 3.4

From reactions of samples IV-VI it is obvious that with increasingreplacement of Cl against H in the methylchlorodisilanes MenSi₂Cl_(6-n)with Cl≥3, the partial hydrido substituted disilanes were cleavedsignificantly faster. Cleavage of disilanes with Me≥4 (partial orperhydrogenated) required higher temperatures. At about 140° C. mainlythe chlorosilanes Me₂SiCl₂, Me₃SiCl, Me₂SiHCl and MeSiHCl₂ were formed.Investigation of the reactions by ³¹P-NMR spectroscopy proved theactivity of n-Bu₄PCl as real catalyst, only at 220° C. and higher, thelatter is completely reacted to give n-Bu₃P, traces of n-Bu₂PH and1-but-ene, and hydrogen chloride that is responsible for the finalformation of H/Cl substituted monosilanes.

Example 20

In a 50 ml flask, a mixture of disilanes Cl₂MeSi-SiMeCl₂ (69 mol %),ClMe₂Si—SiMeCl₂ (26 mol %), ClMe₂Si—SiMe₂Cl (4 mol %) and Me₃Si—SiMeCl₂(1 mol %) (244 mg) was reacted with Ph₄PCl (25.3 mg) and LiH (202 mg) in0.5 mL of diglyme. Already at r.t. 75 mol % of monosilanes were formed,with compound 8 obtained in an amount of 40 mol %. 25 mol % of disilanesremained uncleaved, 10 mol % of those were reduced (SiCl—SiH) (Table29). MeSiH₃ that might have been formed evaporated in the open systemdue to its low boiling point (−57° C.). That is why the same disilanemixture (122 mg) was reacted with the catalyst/LiH (1 w %/4 w %) in asealed NMR tube at r.t. In this case monosilane 10 was detected in 13mol % yield, the compound 8 was formed in 21 mol % and compound 9 in 33mol % yield.

TABLE 29 no. silane mol % 8 MeSiHCl₂ 40 12 Me₂SiHCl 9 9 MeSiH₂Cl 10 11Me₂SiCl₂ 10 14 Me₃SiCl 2 7 MeSiCl₃ 4 1 Cl₂MeSi—SiMeCl₂ 4 3ClMe₂Si—SiMe₂Cl 1 2 ClMe₂Si—SiMeCl₂ 9 4 Me₃Si—SiMeCl₂ 1 24MeH₂Si—SiMeCl₂ 2 25 MeH₂Si—SiMeHCl 6 17 HMe₂Si—SiMeH₂ 1 16 MeH₂Si—SiMeH₂1

Example 21

This Example 21 illustrates the desirable changes in composition of theproduct from the Rochow-Müller Direct Synthesis brought about bytreating the crude methylchlorosilane mixture with LiH. Consider thatthe Rochow-Müller Direct Synthesis is occurring at 290° C./4 atm in acommercial-scale fluidized-bed reactor containing about 45 metric tonscopper-activated silicon. Silicon conversion is 4.5%/h, which yieldsabout 9300 kg/h methylchlorosilane crude. All, or a portion, of thiscrude is treated with LiH to increase formation ofmethylchlorohydridosilanes, particularly Me₂SiHCl.

Table 30 lists compositions of two samples of the crudemethylchlorosilanes, as well as the quantities (in grams per metric ton)of each component. Molar amounts per metric ton and the total moles ofchloride are shown in Table 31. These data enable calculation of themolar and gravimetric amounts of LiH required to produce desiredquantities of methylchlorohydridosilanes.

TABLE 30 Gravimetric Composition of Products from Rochow - Müller DirectSynthesis SAMPLE A SAMPLE B COMPOUND wt % g/MT wt % g/MT (CH₃)₄Si TraceTrace HSiCl₃ Trace Trace (CH₃)₂SiHCl (M2H) 0.09 901.35 1.10 11024.2CH₃SiHCl₂ (MH) 1.34 13420.1 4.69 46902.96 (CH₃)₃SiCl (M) 1.76 17626.42.05 20545.1 CH₃SiCl₃ (T) 3.96 39559.25 5.17 51713.52 (CH₃)₂SiCl₂ (D)90.19 901850.75 82.87 828719.18 (CH₃)₃SiSi(CH₃)₃ 0.01 90.16 0.01 123.71(CH₃)₃SiSi(CH₃)₂Cl 0.05 452.04 0.06 620.28 Cl(CH₃)₂SiSi(CH₃)₂Cl 0.09876.33 0.12 1202.49 (CH₃)₃SiSi(CH₃)Cl₂ 0.07 737.97 0.10 1012.62Cl(CH₃)₂SiSi(CH₃)Cl₂ 0.94 9386.70 1.29 12880.25 Cl₂(CH₃)SiSi(CH₃)Cl₂1.51 15056.80 2.07 20660.65 T/D 0.044 0.062 MT = Metric ton (1000 kg)

Here, it is useful to recall

-   -   that methylchlorodisilanes are reduced and cleaved by LiH    -   that the order of reactivity of the methylchlorosilanes with LiH        is CH₃SiCl₃>(CH₃)₂SiCl₂>(CH₃)₃SiCl    -   and CH₃SiH₂Cl>CH₃SiHCl₂>CH₃SiCl₃    -   and (CH₃)₂SiHCl>(CH₃)₂SiCl₂

TABLE 31 Molar Composition of Products from Rochow - Müller DirectSynthesis SAMPLE A, SAMPLE B, COMPOUND mol/MT mol/MT (CH₃)₂SiHCl (M2H)9.53 116.51 CH₃SiHCl₂ (MH) 116.67 407.75 (CH₃)₃SiCl (M) 162.25 189.11CH₃SiCl₃ (T) 264.65 345.96 (CH₃)₂SiCl₂ (D) 6987.84 6421.19(CH₃)₃SiSi(CH₃)₃ 0.62 0.85 (CH₃)₃SiSi(CH₃)₂Cl 2.71 3.72Cl(CH₃)₂SiSi(CH₃)₂Cl 4.68 6.42 (CH₃)₃SiSi(CH₃)Cl₂ 3.94 5.41Cl(CH₃)₂SiSi(CH₃)Cl₂ 45.21 62.04 Cl₂(CH₃)SiSi(CH₃)Cl₂ 66.03 90.61 TOTALCHLORIDE, mol/MT 15351.56 14645.26 LiH (g) for 55 mol % Use 67125 64036LiH (g) for 110 mol % Use 134249 128073

The remaining calculations are based on the use of 67 kg LiH (value fromTable 31, row 14) to treat 1 metric ton of MCS crude having thecompositions shown in Table 30.

TABLE 32 Reduction of Methylchlorosilanes by LiH PRODUCTS FORMED. DATAIN mol % SILANE LiH, mol % (CH₃)₃SiCl (CH₃)₃SiH (CH₃)₃SiCl 55 50 50 110   0 100  (CH₃)₂SiCl₂ (CH₃)₂SiHCl (CH₃)₂SiH₂ (CH₃)₂SiCl₂ 55 48 4 48 110   0 0 100  CH₃SiCl₃ CH₃SiHCl₂ CH₃SiH₂Cl CH₃SiH₃ CH₃SiCl₃ 55 49 1 2 48 110   0 0 0 100

²⁹Si NMR spectroscopy was used to obtain the data disclosed in Tables 32on the reaction of individual methylchlorosilanes with LiH. LiH cleavageof the individual methylchlorodisilanes was also studied by ²⁹Si NMRspectroscopy. The data are displayed in Table 33.

TABLE 33 Cleavage of individual methylchlorodisilanes by LiH REACTIONPRODUCTS FORMED. DATA IN mol % DISILANE WITH LiH, % (CH₃)₃SiX (CH₃)₂SiX₂CH₃S1X₃ (CH₃)₃SiSi(CH₃)₂Cl  5* 95 5 Cl(CH₃)₂SiSi(CH₃)₂Cl  10* 5 95(CH₃)₃SiSi(CH₃)Cl₂ 75 90 10 Cl(CH₃)₂SiSi(CH₃)Cl₂ 75 90 10Cl₂(CH₃)SiSi(CH₃)Cl₂ 80 1 99 *Highly methylated disilanes react only toa limited extent with LiH. X = Cl, H.

The data in Tables 32 and 33 are used in conjunction with the results ofother redistribution experiments in co-pending applications to arrive atthe final compositions shown in Table 34

TABLE 34 Final Product Compositions After Reduction, Cleavage andRedistribution SAMPLE A SAMPLE B COMPOUND wt % g/MT wt % g/MT CH₂SiH₃0.01 103.56 0.03 195.07 (CH₃)₂SiH₂ 8.69 64147.05 7.87 55750.15 CH₃SiH₂Cl3.36 24805.64 4.60 32537.87 (CH₃)₃SiH 0.00 0 0.00 0 (CH₃)₂SiHCl (M2H)61.79 456374.71 60.75 430182.72 CH₃SiHCl₂ (MH) 0.10 737.63 0.17 1215.78(CH₃)₃SiCl (M) 6.30 46549.75 8.51 60233.16 CH₃SiCl₃ (T) 0.00 0 0.00 0(CH₃)₂SiCl₂ (D) 19.75 145838.12 18.07 127955.50 T/D 0 0 TOTAL MCSWEIGHT, g 738556.45 708070.24 TOTAL LiCl PRODUCED, g 325407 310436

The results of these Examples demonstrate that the use of only 6.7weight percent LiH can alter the composition of the product from theRochow-Müller Direct Synthesis from being primarilydimethyldichlorosilane (D) to primarily dimethylchlorosilane (M2H).

Methyltrichlorosilane (T) is consumed and trimethylchlorosilane (M) isincreased. The product yield is approximately 71-74%. Volatilehydridosilanes (CH₃SiH₃, (CH₃)₂SiH₂ and CH₃SiH₂Cl) can be recovered andadded to fresh Rochow-Müller Direct Synthesis product, or reused inredistribution with methylchlorosilanes. Overall, more valuable monomersare obtained. Additionally, LiCl (>300 kg) produced can be recovered andused to produce Li and LiH.

Example 22 On the Recovery of LiCl for Manufacture of Li and LiH

This Example illustrates the recovery, purification and characterizationof LiCl produced when LiH was used in the reduction of (CH₃)₂SiCl₂ to(CH₃)₂SiHCl and (CH₃)₂SiH₂ as is described in co-pending applications.

Solid from the reaction was recovered by filtration and treated withdiglyme saturated with gaseous HCl to convert any unreacted LiH to LiCl.It was then washed four times with dry pentane and dried in vacuo at630° C. for one hour.

The LiCl was dissolved in diglyme and C₆D₆ characterized by ⁷Li-NMRrecorded on a Bruker AV-500 spectrometer.

The single resonance observed (6=0.23 ppm) is assignable to the chemicalshift of LiCl by comparison with an authentic sample of LiCl (6=0.20ppm).

The dried LiCl was mixed with KCl in the proportions shown in the Tablebelow. Melting behavior of the samples was recorded by a camera attachedto the automated melting point apparatus, OptiMelt MPA 100. Forcomparison, the melting behavior of authentic LiCl—KCl samples was alsomeasured. Both sets of data are shown in the Table 35.

TABLE 35 WEIGHT MELTING POINTS, ° C. MELTING POINTS, ° C. RATIOS,RECOVERED AUTHENTIC LiCLKCl LiCLKCl LiCLKCl 40:60 355.3 354.8 50:50356.1 355.6 60:40 355.9 356.6

The observed melting points for the recovered and control samples are ingood agreement with each other. The 40:60 LiCl—KCl sample corresponds tothe eutectic composition. The melting point observed is consistent withpublished values (see S. Zemczuzny, et al., Zeitschrift für AnorganischeChemie, 46 (1910) 403-428). The melting point data prove that therecovered LiCl forms a pure eutectic with KCl and thereby satisfies oneof the quality criteria for electrolytic Li recovery.

Example 23

To prove the assumption of Example 21 and to elucidate optimum reactionconditions for the formation of Me₂SiHCl in high yields, the complexcrude mixture of the Rochow-Müller Direct Process was simulated byadmixing the single compounds in a molar ratio listed in Table 36, withMe₂SiCl₂ as the main component (91.65 mol %), MeSiCl₃ being present in4.85 mol %.

TABLE 36 Density M of the of the M ²⁹Si-NMR mixture Chlorine Densitymixture Compound [g/mol] integrals Mol % [g/mol] in mixture [g/ml][g/ml] Me₂SiCl₂ 129.06 1 91.646 118.28 1.832928 1.064 0.97511 Me₃SiCl108.64 0.0216 1.980 2.15 0.019795 0.856 0.01694 MeSiCl₃ 149.48 0.05294.848 7.25 0.145442 1.273 0.06171 Me₅Si₂Cl 166.8 0.0003 0.027 0.050.000274 0.862 0.00023 (ClMe₂Si)₂ 187.21 0.0003 0.027 0.05 0.0005491.006 0.00027 (Cl₂MeSi)₂ 228.04 0.01025 0.939 2.14 0.037575 1.2690.01192 ClMe₂Si—SiMeCl₂ 207.63 0.0055 0.504 1.05 0.015121 1.13 0.00569Me₃Si—SiMeCl₂ 187.21 0.0003 0.027 0.05 0.000549 1.006 0.00027 Total —1.09115 100 131.01 2.052238 — 1.072

The chlorosilane reductions, the disilane cleavage reaction andSi—H/Si—Cl redistribution with about 1 to about 5 wt-% nBu₄PCl wereperformed in sealed NMR tubes to prevent evaporation of low boilingcomponents, such as Me₂SiH₂ and MeSiH₃. In case n-Bu₄PCl decomposesrunning the reactions, n-Bu₃P forms in addition to (poly-) but-1-ene andhydrogen chloride that is responsible for increasing formation ofhydrido substituted monosilanes and/or additional chlorination of Si—Hbonds (of mono- and disilanes) in to Si—Cl moieties. The products formedupon heating the reaction mixtures and the conversion rates of lithiumhydride are given in mol % and are listed in Table 37 for diglyme assolvent.

TABLE 37¹⁾ Diglyme Conversion 40 mol % of LiH LiH Me₂SiCl₂ Me₃SiClMe₂SiHCl MeSiHCl₂ MeSiH₂Cl Me₂SiH₂ MeSiH₃ [%] Remarks r.t., 12, 74.1 1.59.6 0.7 1.5 5.9 6.7 42 0% Decomposition of 6 h nBu₄PCl 60° C., 52.5 1.627.8 — 0.8 8.9 8.4 68 1% Decomposition of 2 h nBu₄PCl 70° C., 41.2 1.340.3 — 1.6 8.2 7.4 76 2% Decomposition of 2 h nBu₄PCl 70° C., 37.3 1.944.4 1.5 8.2 6.7 79 2% Decomposition of 2 h nBu₄PCl 80° C., 34.1 1.748.5 — 2.4 7.2 6.1 80 3% Decomposition of 2 h nBu₄PCl 90° C., 32.0 1.652.4 — 1.9 6.4 5.8 81 3% Decomposition of 2 h nBu₄PCl 100° C., 30.3 1.853.7 — 1.8 6.7 5.8 83 3% Decomposition of 2 h nBu₄PCl 110° C., 25.9 1.654.1 — 2.1 9.8 6.5 91 5% Decomposition of 2 h nBu₄PCl 120° C., 25.3 1.755.0 — 2.0 8.8 7.0 92 5% Decomposition of 2 h nBu₄PCl 130° C., 25.2 1.354.9 — 2.0 9.3 7.3 93 5% Decomposition of 2 h nBu₄PCl 130° C., 24.0 1.754.7 — 1.9 10.1 7.7 95 5% Decomposition of 2 h nBu₄PCl 135° C., 23.5 1.454.9 — 1.9 10.3 8.0 96 5% Decomposition of 4 h nBu₄PCl 140° C., 21.7 1.354.8 — 1.7 12.1 8.4 100 5% Decomposition of 2 h nBu₄PCl 150° C., 21.81.5 54.7 — 1.7 12.2 8.1 100 5% Decomposition of 4 h nBu₄PCl ¹⁾NMR scalereaction to prove the conditions for reduction, cleavage andredistribution reactions. For the reaction 40 mol % LiH (in relation tothe total chlorine content present in the silane mixture) was used toconvert. The concentration of LiH was 17 mol/L related to the solvent.C₆D₆ (0.2 mL) was added as NMR standard. C₆D₆ is not able to dissolveLiH or LiCl and should not have any affect on the reactions. Reactionswere started at room temperature and were controlled increasingtemperature form 60° C. in 10° C. steps. ⁷Li-NMR-shifts of LiCl inDiglyme: 0.56 ppm, in 1,4-dioxane: 1.11 ppm and in THF: 0.87 ppm.between 5 to 10 wt.

Table 38 contains data obtained for comparable reactions, but in thepresence of 7 mol % of the crown ether 12-crown-4 in the reactionmixture. In the latter case chlorosilane reduction started only at 80°C., at 100° C. the amount of Me₂SiHCl is >40 mol %, while the molarconcentration of Me₂SiH₂ is very low (3.2 mol %). At temperature above110° C. the strong formation of solids prevents further NMRinvestigations on the product mixture.

TABLE 38¹⁾ Diglyme + Conversion 7 vol % of LiH crown Me₂SiCl₂ Me₃SiClMe₂SiHCl MeSiHCl₂ MeSiH₂Cl Me₂SiH₂ MeSiH₃ [%] Remarks r.t., 12, 92.9 2.8— — — — — 0 0% Decomposition of 6 h nBu₄PCl 3.8% MeSiCl₃ <1% disilanes60° C., 92.9 2.8 — — — — — 0 0% Decomposition of 2 h nBu₄PCl 3.8%MeSiCl₃ <1% disilanes 80° C., 84.7 1.7 0.9 — — 5.1 6.8 40 0%Decomposition of 2 h nBu₄PCl 0.9% MeSiCl₃ 90° C., 74.1 1.5 16.3 — — 1.56.7 49 0% Decomposition of 2 h nBu₄PCl 100° C., 45.2 1.8 41.2 1.8 3.23.2 3.6 83 1% Decomposition of 2 h nBu₄PCl 110° C., NMR analysis failedbecause of too much solids in the NMR tube — 2 h 120° C., NMR analysisfailed because of too much solids in the NMR tube — 2 h ¹⁾NMR scalereaction to prove the conditions for reduction, cleavage andredistribution reactions. For the reaction 40 mol % LiH (in relation tothe total chlorine content present in the silane mixture) was used toconvert. The concentration of LiH was 17 mol/L in relation to thesolvent. C₆D₆ (0.2 mL) was added as NMR standard. C₆D₆ is not able todissolve LiH or LiCl and should not have any affect on the reactions.Reactions were started at room temperature and were controlledincreasing temperature form 60° C. in 10° C. steps. ⁷Li-NMR-shifts ofLiCl in Diglyme: 0.56 ppm, in 1,4-dioxane: 1.11 ppm and in THF: 0.87ppm.

TABLE 39¹⁾ Conversion 1,4- of LiH dioxane Me₂SiCl₂ Me₃SiCl Me₂SiHClMeSiHCl₂ MeSiH₂Cl Me₂SiH₂ MeSiH₃ [%] Remarks r.t., 12, 60.6 1.8 21.8 —0.6 7.9 7.3 63 0% Decomposition of 6 h nBu₄PCl 60° C., 42.0 1.3 42.8 — —8.4 5.5 79 0% Decomposition of 2 h nBu₄PCl 70° C., 34.6 1.7 49.5 — 1.46.6 6.2 87 1% Decomposition of 2 h nBu₄PCl 70° C., 32.3 1.6 53.4 — 0.76.5 5.5 88 2% Decomposition of 2 h nBu₄PCl 80° C., 31.2 1.3 54.5 — 0.36.5 6.2 90 2% Decomposition of 2 h nBu₄PCl 90° C., 29.4 1.2 55.8 — — 7.16.5 93 2% Decomposition of 2 h nBu₄PCl 100° C., 30.0 1.2 55.6 — — 6.96.3 92 2% Decomposition of 2 h nBu₄PCl 110° C., 28.9 1.4 55.4 — — 8.16.1 93 2% Decomposition of 2 h nBu₄PCl 120° C., 27.9 1.4 55.0 — — 8.17.5 97 2% Decomposition of 2 h nBu₄PCl 130° C., 28.7 1.4 55.5 — — 7.27.2 95 2% Decomposition of 2 h nBu₄PCl 130° C., 27.7 1.7 54.3 — 1.4 8.06.9 97 2% Decomposition of 2 h nBu₄PCl 135° C., 27.8 1.7 55.0 — — 8.07.5 97 2% Decomposition of 4 h nBu₄PCl 140° C., 27.9 1.4 54.5 — — 8.47.8 98 2% Decomposition of 2 h nBu₄PCl 150° C., 26.7 1.6 53.3 — 2.1 8.38.0 100 2% Decomposition of 4 h nBu₄PCl ¹⁾NMR scale reaction to provethe conditions for reduction, cleavage and redistribution reactions. Forthe reaction 48 mol % LiH (in relation to the total chlorine contentpresent in the silane mixture) was used to convert. The concentration ofLiH was 17 mol/L related to the solvent. C₆D₆ (0.2 mL) was added as NMRstandard. C₆D₆ is not able to dissolve LiH or LiCl and should not haveany affect on the reactions. Reactions were started at room temperatureand were controlled increasing temperature form 60° C. in 10° C. steps.⁷Li-NMR-shifts of LiCl in Diglyme: 0.56 ppm, in 1,4-dioxane: 1.11 ppmand in THF: 0.87 ppm.

Table 39 covers the results for comparable reactions but in 1,4-dioxaneas solvent, Table 40 shows the results obtained with the addition of 7mol % of 12-crown-4-ether. In this case the observations made were verysimilar to those results described for the reaction in diglyme withaddition of 12-crown-4-ether (Table 38).

TABLE 40¹⁾ Dioxane + Conversion 7 vol % of LiH crown Me₂SiCl₂ Me₃SiClMe₂SiHCl MeSiHCl₂ MeSiH₂Cl Me₂SiH₂ MeSiH₃ [%] Remarks r.t., 12, 92.9 2.8— — — — — 0 0% Decomposition of 6 h nBu₄PCl 3.8% MeSiCl₃ <1% disilanes60° C., 92.9 2.8 — 0.6 — — — 1 0% Decomposition of 2 h nBu₄PCl 3.2%MeSiCl₃ <1% disilanes 80° C., 75.6 2.3 13.7 — 0.8 1.5 6.0 46 0%Decomposition of 2 h nBu₄PCl 90° C., 60.6 1.8 16.4 — — 14.5 6.7 82 0%Decomposition of 2 h nBu₄PCl 100° C., 40.6 1.7 45.1 — 2.0 5.3 5.3 95 1%Decomposition of 2 h nBu₄PCl 110° C., 35.5 1.4 49.2 — 1.1 7.1 5.7 111 1%Decomposition of 2 h nBu₄PCl 120° C., NMR analysis failed because of toomuch solids in the NMR tube — 2 h ¹⁾NMR scale reaction to prove theconditions for reduction, cleavage and redistribution reactions. For thereaction 40 mol % LiH (in relation to the total chlorine content presentin the silane mixture) was used to convert. The concentration of LiH was17 mol/L related to the solvent. C₆D₆ (0.2 mL) was added as NMRstandard. C₆D₆ is not able to dissolve LiH or LiCl and should not haveany affect on the reactions. Reactions were started at room temperatureand were controlled increasing temperature form 60° C. in 10° C. steps.⁷Li-NMR-shifts of LiCl in Diglyme: 0.56 ppm, in 1,4-dioxane: 1.11 ppmand in THF: 0.87 ppm.

The reactions performed in THF as solvent are listed in Table 41, thoseruns in the presence of 12-crown-4-ether in Table 42. Reaction performedin THF generally show high LiH conversion rates and formation of thetarget compound Me₂SiHCl in high yields under moderate reactionconditions.

TABLE 41¹⁾ Conversion of LiH THF Me₂SiCl₂ Me₃SiCl Me₂SiHCl MeSiHCl₂MeSiH₂Cl Me₂SiH₂ MeSiH₃ [%] Remarks r.t., 12, 54.9 1.7 23.7 — — 11.5 8.261 0% Decomposition of 6 h nBu₄PCl 60° C., 30.6 1.5 48.0 — — 12.3 7.6 811% Decomposition of 2 h nBu₄PCl 70° C., 22.4 1.3 55.1 — 1.3 11.6 7.6 882% Decomposition of 2 h nBu₄PCl 70° C., 21.2 1.2 57.2 — 1.4 11.9 7.1 892% Decomposition of 2 h nBu₄PCl 80° C., 20.8 1.5 56.6 — 1.6 12.0 7.5 902% Decomposition of 2 h nBu₄PCl 90° C., 20.4 1.4 56.9 — 1.2 12.4 7.7 902% Decomposition of 2 h nBu₄PCl 100° C., 19.9 1.4 57.6 — 0.8 12.9 7.4 912% Decomposition of 2 h nBu₄PCl 110° C., 18.7 1.3 57.1 — 1.1 13.9 7.9 932% Decomposition of 2 h nBu₄PCl 120° C., 18.2 1.4 56.0 — 1.1 14.6 8.7 953% Decomposition of 2 h nBu₄PCl 130° C., 18.4 1.3 56.1 — 1.1 14.8 8.3 953% Decomposition of 2 h nBu₄PCl 130° C., 17.4 1.4 55.6 — 0.7 16.5 8.5 973% Decomposition of 2 h nBu₄PCl 135° C., 17.0 1.4 56.4 — — 16.6 8.6 973% Decomposition of 4 h nBu₄PCl 140° C., 16.7 1.5 56.2 — — 16.5 9.2 993% Decomposition of 2 h nBu₄PCl 150° C., 16.4 1.3 54.2 — 1.3 18.2 8.5100 3% Decomposition of 4 h nBu₄PCl ¹⁾NMR scale reaction to prove theconditions for reduction, cleavage and redistribution reactions. For thereaction 59 mol % LiH (in relation to the total chlorine content presentin the silane mixture) was used to convert. The concentration of LiH was17 mol/L (in relation to the solvent). C₆D₆ (0.2 mL) was added as NMRstandard. C₆D₆ is not able to dissolve LiH or LiCl and should not haveany affect on the reactions. Reactions were started at room temperatureand were controlled increasing temperature form 60° C. in 10° C. steps.⁷Li-NMR-shifts of LiCl in Diglyme: 0.56 ppm, in 1,4-dioxane: 1.11 ppmand in THF: 0.87 ppm.

TABLE 42¹⁾ THF + Conversion 7 vol % of LiH crown Me₂SiCl₂ Me₃SiClMe₂SiHCl MeSiHCl₂ MeSiH₂Cl Me₂SiH₂ MeSiH₃ [%] Remarks r.t., 12, 92.9 2.8— — — — — 0 0% Decomposition of 6 h nBu₄PCl 3.8% MeSiCl₃ <1% disilanes60° C., 92.9 2.8 0.2 1.0 — — — 2 0% Decomposition of 2 h nBu₄PCl 2.6%MeSiCl₃ <1% disilanes 80° C., 75.8 1.5 4.5 — — 11.4 6.8 58 0%Decomposition of 2 h nBu₄PCl 90° C., 54.0 1.6 34.6 0.5 2.7 2.2 4.3 70 1%Decomposition of 2 h nBu₄PCl 100° C., 45.0 1.8 41.0 1.4 3.1 3.2 4.5 831% Decomposition of 2 h nBu₄PCl 110° C., 44.0 1.8 43.6 0.4 2.7 2.7 4.884 3% Decomposition of 2 h nBu₄PCl 120° C., 43.7 1.7 44.1 — 3.1 3.1 4.484 3% Decomposition of 2 h nBu₄PCl 130° C., 38.7 1.6 48.1 — 3.0 3.9 4.792 3% Decomposition of 2 h nBu₄PCl 130° C., 39.2 1.6 47.8 — 3.1 3.1 5.191 3% Decomposition of 2 h nBu₄PCl 130° C., 38.9 1.6 47.9 — 3.1 3.5 5.192 3% Decomposition of 2 h nBu₄PCl 130° C., 37.2 1.5 48.7 — 3.0 4.1 5.696 3% Decomposition of 2 h nBu₄PCl 135° C., 36.2 1.5 49.0 — 2.9 4.3 6.099 3% Decomposition of 4 h nBu₄PCl 140° C., 35.0 1.4 50.7 — 1.7 4.9 6.3100 3% Decomposition of 2 h nBu₄PCl 150° C., 34.6 1.7 50.5 — 2.8 5.2 5.2100 3% Decomposition of 4 h nBu₄PCl ¹⁾NMR scale reaction to prove theconditions for reduction, cleavage and redistribution reactions. For thereaction 41 mol % LiH (in relation to the total chlorine content presentin the silane mixture) was used to convert. The concentration of LiH was17 mol/L (in relation to the solvent). C₆D₆ (0.2 mL) was added as NMRstandard. C₆D₆ is not able to dissolve LiH or LiCl and should not haveany affect on the reactions. Reactions were started at room temperatureand were controlled increasing temperature form 60° C. in 10° C. steps.⁷Li-NMR-shifts of LiCl in Diglyme: 0.56 ppm, in 1,4-dioxane: 1.11 ppmand in THF: 0.87 ppm

Example 24

Based on the experiments of Example 23 that were performed with about 1to about 5 wt-% nBu₄PCl in sealed NMR tubes in only small amounts ofreactants, similar experiments were run in sealed reaction ampules withvarying gram-amounts of chlorosilanes, molar composition is given inTable 36. In a detailed study different reaction conditions wereinvestigated that are listed under “Remarks” in the Tables.

Table 43 covers the results obtained for reactions in different glymesas solvent: The reaction temperatures were between 110° C. and 150° C.for 60-65 h. The LiH conversion rates were 60-90 mol %, the lower theLiH concentration (in mol/L) the higher were the conversion rates.Obtained yields for Me₂SiHCl were 30-55 mol %, if the amount of Me₂SiH₂(<30 mol %) is added, the yield of Me₂SiHCl is nearly quantitativelyincluding post processing reactions such as reactions with the ether/HClreagent (patent pending), or redistribution with Me₂SiCl₂. Remarkablyquite strong decomposition of n-Bu₄PCl to give n-Bu₃P besides otherphosphine compounds and but-1-ene is observed in some cases, the in situformed HCl acting as chlorination reagent to retransfer Si—H bonds intoSi—Cl.

TABLE 43 Weight Exchange LiH— Conversion of MCS of H/Cl concentration ofLiH [%] [g] [mol %] [mol/L] M2 M3 M2H MH MH2 M2H2 MH3 (±3%) Remarks 13.851 16.9 50.5 2.0 37.0 2.0 4.0 2.0 3.0 60 Solvent: Diglyme, 110° C., 65 h4% Decomposition of nBu₄PCl Corresponds to 30 mol % LiH 9.8 48 10.6 48.31.9 38.2 1.9 3.9 1.9 3.9 66 Solvent: Diglyme, 110° C., 65 h 3%Decomposition of nBu₄PCl Corresponds to 31 mol % LiH 10.9 48 10.6 46.31.9 40.7 1.9 3.2 2.3 3.7 67 Solvent: Triglyme, 110° C., 65 h 3%Decomposition of nBu₄PCl Corresponds to 31 mol % LiH 9.4 48 10.6 48.31.9 40.1 1.0 2.9 1.9 3.9 65 Solvent: Tetraglyme, 110° C., 65 h 0%Decomposition of nBu₄PCl Corresponds to 31 mol % LiH 5.0 81 25.7 28.52.0 54.70 — 1.1 9.7 4.0 56 Solvent: Diglyme 110° C., 4 h; 130° C., 65 h44% Decomposition of nBu₄PCl Corresponds to 44 mol % LiH 4.8 81 5.0 20.01.8 56.4 — 1.0 16.0 4.8 65 Solvent: Diglyme 110° C., 4 h; 130° C., 65 h26% Decomposition of nBu₄PCl Corresponds to 52 mol % LiH 4.0 81 2.0 9.31.3 53.1 — — 28.3 8.0 83 Solvent: Diglyme 110° C., 4 h; 130° C., 65 h 0%Decomposition of nBu₄PCl Corresponds to 64 mol % LiH 7.5 43 10.0 59.21.8 30.2 2.4 3.5 1.1 1.8 57 Solvent: Diglyme, 130° C., 60 h 5%Decomposition of nBu₄PCl Corresponds to 24 mol % LiH 5.7 65 10.0 40.51.6 46.6 0.8 1.6 4.9 4.0 56 Solvent: Diglyme, 130° C., 60 h 30%Decomposition of nBu₄PCl Corresponds to 35 mol % LiH 5.3 86 10.0 25.62.3 39.3 — 1.0 24.4 7.4 65 Solvent: Diglyme, 130° C., 60 h 30%Decomposition of nBu₄PCl Corresponds to 54 mol % LiH 3.8 118 25.0 22.41.6 43.3 — 0.2 28.9 3.6 49 Solvent: Diglyme, 150° C., 60 h 100%Decomposition of nBu₄PCl Corresponds to 56 mol % LiH 6.1 47 1.25 34.52.0 48.3 — 3.8 4.8 6.4 89 Solvent: Diglyme, 130° C., 62 h 0%Decomposition of nBu₄PCl Corresponds to 42 mol % LiH 6.8 39 1.25 47.61.9 38.1 1.4 3.8 2.4 4.7 84 Solvent: Diglyme, 120° C., 62 h 0%Decomposition of nBu₄PCl Corresponds to 33 mol % LiH 5.0 48 1.25 35.11.8 47.7 — 2.8 6.0 6.6 89 Solvent: Diglyme, 120° C., 62 h 0%Decomposition of nBu₄PCl Corresponds to 43 mol % LiH 8.5 30 1.25 56.21.7 31.5 2.2 3.9 1.1 3.4 88 Solvent: Diglyme, 120° C., 62 h 0%Decomposition of nBu₄PCl Corresponds to 27 mol % LiH 4.9 51 17 35.2 2.147.9 1.4 2.8 3.9 6.7 80 Solvent: Diglyme 12-crown-4 10vol %, 130° C., 65h 0% Decomposition of nBu₄PCl Corresponds to 41 mol % LiH 5.4 51 17 47.21.9 38.7 1.9 3.8 1.9 4.7 64 Solvent: Diglyme Addition of KCl, 130° C.,65 h 0% Decomposition of nBu₄PCl Corresponds to 33 mol % LiH M2 =Me₂SiCl₂, M3 = Me₃SiCl, M2H = Me₂SiHCl, MH = MeSiHCl₂, MH2 = MeSiH₂Cl,M2H2 = Me₂SiH₂ and MH3 = MeSiH₃

More efficient are comparable reactions in THF as solvent (Table 44),giving high LiH conversion rates for e.g. with 17 molarLiH-concentrations—eventually in the presence of crown-ether—they reach100 mol %. In this case the yield of Me₂SiHCl is ˜56 mol %, Me₂SiH₂ isformed in ˜17 mol %: Including post processing of the dihydridosilanesthe overall yield of Me₂SiHCl will be about 90 mol %. In the presence ofcrown-ether a solid residue is formed with LiCl adduct formation thatcan be split again thermally at ˜100° C. into the starting materials andthus will be recycled quantitatively (G. Shore et al., Inorg. Chem.1999, 38, 4554-4558). In a similar way 1,4-dioxane forms with LiCl athermo-labile complex that will be split into the adduct formingcomponents at higher temperatures (S. Yamashita et al., MassSpectroscopy, 11, 106 (1963); 28, 211-216 (1965)). These two findingsexplain strong solid formation using 1,4-dioxane as solvent, especiallyin the presence of crown-ethers. That might facilitate productseparation because hydridochlorosilanes might be separated from “solid”solvent and/or crown-ether easily with subsequent recycling of theethers at ˜100° C.

TABLE 44 Weight Exchange LiH— Conversion of MCS of H/Cl concentration ofLiH [%] [g] [mol %] [mol/L] M2 M3 M2H MH MH2 M2H2 MH3 (±3%) Remarks 4.751 17 35.5 2.0 50.8 0.7 2.0 8.8 3.2 82 Solvent: THF, 130° C., 65 h 36%Decomposition of nBu₄PCl Corresponds to 42 mol % LiH 4.1 51 17 46.3 1.941.6 1.9 2.3 2.3 3.7 63 Solvent: DME, 130° C., 65 h 26% Decomposition ofnBu₄PCl Corresponds to 32 mol % LiH 7.6 53 17 24.9 2.1 45.6 0.0 1.0 21.64.81 101 Solvent: THF 12-crown-4 5 vol %, 130° C., 65 h 10%Decomposition of nBu₄PCl 18.4 1.8 56.1 — 1.1 17.1 5.5 103 Aftercondensation of all volatile compounds (work up) 8.8 51 17 46.7 1.9 41.11.0 2.3 2.3 4.7 64 Solvent: DME 12-crown-4 5 vol %, 130° C., 65 h 10%Decomposition of nBu₄PCl Corresponds to 33 mol % LiH 12.0 51 17 46.5 1.939.5 1.9 3.7 2.8 3.7 64 Solvent: Dioxane, 130° C., 65 h 7% Decompositionof nBu₄PCl Corresponds to 33 mol % LiH 48.3 1.9 40.6 1.9 3.4 1.9 2.9 60After condensation of all volatile compounds (work up) 13.7 51 17 41.71.7 43.3 0.8 3.3 3.8 3.4 73 Solvent: Dioxane 12-crown-4 2 vol %, 130°C., 65 h 6% Decomposition of nBu₄PCl Corresponds to 73 mol % LiH 12.1 5110 41.2 1.6 43.6 0.8 2.9 5.8 4.1 73 Solvent: THF 130° C., 65 h 76%Decomposition of nBu₄PCl Corresponds to 37 mol % LiH 16.8 39 11 55.2 1.733.2 2.2 3.8 1.2 2.9 69 Solvent: Dioxane (1:1 in mol dioxane:LiH), 130°C., 64 h 5% Decomposition of nBu₄PCl Corresponds to 27 mol % LiH 17.9 3914 53.9 1.7 33.6 2.2 3.2 2.2 3.2 72 Solvent: Dioxane/THF (1:1), 130° C.,64 h 2% Decomposition of nBu₄PCl Corresponds to 28 mol % LiH 12.2 39 1450.8 2.0 35.6 2.0 4.0 2.0 3.6 78 Solvent: Dioxane/THF (1:1), 12-crown-43 vol %, 130° C., 64 h 2% Decomposition of nBu₄PCl Corresponds to 28 mol% LiH 4.6 51 17 Solvent: DMF, 130° C., 65 h; Reaction with DMF gives 90%of non-identified compounds 8.8 51 17 Solvent: DMF, 12-crown-4 5 vol %,130° C., 65 h; Reaction with DMF gives 90% of non-identified compoundsM2 = Me₂SiCl₂, M3 = Me₃SiCl, M2H = Me₂SiHCl, MH = MeSiHCl₂, MH2 =MeSiH₂Cl, M2H2 = Me₂SiH₂ and MH3 = MeSiH₃

As can be seen in Table 44, dimethoxyethane (DME) can be used as solventtoo, but shows no significant efforts compared to the other ethers usedin our investigations. The same is true for mixtures of ethers asexemplarily shown for reactions performed in 1/1 mixtures of 1,4-dioxaneand THF.

1. A process for the manufacture of methylchlorohydridomonosilanes,selected from the group consisting of Me₂Si(H)Cl, MeSi(H)Cl₂, andMeSi(H)₂Cl, comprising: subjecting a silane substrate comprising atleast one silane selected from the group consisting of: (i) Monosilanes,(ii) Disilanes, (iii) Oligosilanes, (iv) Carbodisilanes, with theproviso that at least one of the silanes (i) to (iv) has at least onechloro substituent, a) to a hydrogenation reaction with at least onehydride donating source, and b) to a redistribution reaction, and c)optionally to a cleavage reaction of the Si—Si bonds of the di- oroligosilanes or the Si—C-bond of the carbodisilanes, and d) to aseparating step of the methylchlorohydridosilanes. wherein the processis carried out in the presence of one or more solvents, in the absenceof AlCl₃, and wherein (i) the monosilanes are selected from the generalformula (I),Me_(x)SiH_(y)Cl_(z)  (I), wherein x=1 to 3, y=0 to 3, z=0 to 3, andx+y+z=4, (ii) the disilanes are selected from the general empiricalformula (II),Me_(m)Si₂H_(n)Cl_(o)  (II) wherein m=1 to 6, n=0 to 5 o=0 to 5 andm+n+o=6, (iii) oligosilanes are selected from linear or branchedoligosilanes of the general empirical formula (III)Me_(p)Si_(q)H_(r)Cl_(s)  (III), wherein q=3-7 p=q to (2q+2) r, s=0 to(q+2) r+s=(2q+2)−p, (iv) carbodisilanes are selected from the generalformula (IV)(Me_(a)SiH_(b)Cl_(e))—CH₂-(Me_(c)SiH_(d)Cl_(f))  (IV) wherein a, c areindependently of each other 1 to 3, b, d are independently from eachother 0 to 2 e, f are independently from each other 0 to 2, a+b+e=3,c+d+f=3.
 2. A process according to claim 1, wherein the silane substrateis consisting of the silanes of formulas (I) to (IV).
 3. The process ofclaim 1, wherein (i) the monosilanes are selected from the formulas:MeSiCl₃, Me₂SiCl₂, Me₃SiCl, MeSiHCl₂, Me₂SiHCl, MeSiH₂Cl, MeSiH₃,Me₂SiH₂ and Me₃SiH, (ii) the disilanes are selected from the formulas:Cl₂MeSi-SiMeCl₂, Cl₂MeSi-SiMe₂Cl, Cl₂MeSi-SiMe₃ClMe₂Si—SiMe₂Cl,Me₃Si—SiMe₂Cl, HMe₂Si—SiMe₂Cl, H₂MeSi-SiMeClH, HClMeSi-SiMeClH,ClHMeSi-SiMeCl₂, H₂MeSi-SiMeCl₂, HMe₂Si—SiMeCl₂, ClMe₂Si—SiMeH₂,HMe₂Si—SiMeClH, ClMe₂Si—SiMeClH, Me₃Si—SiMeClH, HMe₂Si—SiMe₂H,H₂MeSi-SiMeH₂, HMe₂Si—SiMeH₂, Me₃Si—SiMeH₂ and Me₃Si—SiMe₂H, (iii)oligosilanes are selected from the formulas: ClMe₂Si—SiMe₂-SiMe₂Cl,ClMe₂Si—SiMe₂-SiMe₂-SiMe₂Cl, (ClMe₂Si)₃SiMe, (Cl₂MeSi)₂SiMeCl,(Cl₂MeSi)₃SiMe, (Cl₂MeSi)₂SiMe-SiClMe-SiCl₂Me, [(Cl₂MeSi)₂SiMe]₂,[(Cl₂MeSi)₂SiMe]₂SiClMe, (Cl₂MeSi)₂SiMe-SiMe₂Cl, ClMe₂Si—SiMe₂SiMe₂H,HMe₂Si—SiMe₂-SiMe₂H, HMe₂Si—SiMe₂-SiMe₂-SiMe₂H, (HMe₂Si)₃SiMe,(H₂MeSi)₂SiMeH, (H₂MeSi)₃SiMe, (H2MeSi)2SiMe-SiHMe-SiH2Me,[(H2MeSi)2SiMe]2, [(H2MeSi)2SiMe]2SiHMe and (H2MeSi)2SiMe-SiMe2H, (iv)the carbodisilanes are selected from the formulas: Cl₂MeSi—CH₂—SiMeCl₂,ClMe₂Si—CH₂—SiMeCl₂, ClMe₂Si—CH₂—SiMe₂Cl,Me₃Si—CH₂—SiMeCl₂Me₃Si—CH₂—SiMe₂Cl, HClMeSi—CH₂—SiMeClH,HMe₂Si—CH₂—SiMeCl₂, HMe₂Si—CH₂—SiMe₂Cl, Me₃Si—CH₂—SiMeClH,H₂MeSi—CH₂—SiMeH₂, HMe₂Si—CH₂—SiMeH₂, HMe₂Si—CH₂—SiMe₂H,Me₃Si—CH₂—SiMeH₂, and Me₃Si—CH₂—SiMe₂H, with the proviso that at leastone of the silanes used in the process has at least one chlorosubstituent.
 4. The process of claim 1, wherein the silane substratecomprises at least one silane selected from the group consisting ofMeSiCl₃, Me₂SiCl₂, Me₃SiCl, MeSiHCl₂, Me₂SiHCl, MeSiH₂Cl, MeSiH₃,Me₂SiH₂, Me₃SiH, Cl₂MeSi-SiMeCl₂, Cl₂MeSi-SiMe₂Cl, Cl₂MeSi-SiMe₃,ClMe₂Si—SiMe₂Cl, Me₃Si—SiMe₂Cl, Cl₂MeSi—CH₂—SiMeCl₂,ClMe₂Si—CH₂—SiMeCl₂, ClMe₂Si—CH₂—SiMe₂Cl, Me₃Si—CH₂—SiMeCl₂ andMe₃Si—CH₂—SiMe₂Cl.
 5. The process of claim 1, wherein the hydridedonating source is selected from metal hydrides.
 6. The process of claim1, wherein the redistribution reaction of silanes comprises thecomproportionation of two different methylsilanes, leading to theformation of one specific chlorohydridomethylsilane.
 7. The process ofclaim 1, wherein the redistribution reaction b) is carried out in thepresence of at least one redistribution catalyst,
 8. The process ofclaim 1, wherein the cleavage reaction c) is carried out in the presenceof at least one cleavage catalyst.
 9. The process of claim 1 wherein thehydrogenation reaction a), the redistribution reaction b), andoptionally the cleavage reaction c) are carried out simultaneouslyand/or stepwise.
 10. The process of claim 1, wherein the reactionsequence is selected from one or more of the the following processoptions: the hydrogenation reaction a) and the redistribution reactionb) are carried out simultaneously, the optional cleavage reaction c) iscarried out subsequently, the hydrogenation reaction a), theredistribution reaction b) and the cleavage reaction c) are carried outsimultaneously, at first the hydrogenation reaction a) is carried outseparately, and then the redistribution reaction b) and optionally thecleavage reaction c) are carried out simultaneously or separately,optionally in this embodiment after the hydrogenation reaction a) thealready formed methylchlorohydridomonosilanes can be separated, beforeinducing the redistribution reaction b) and the optional cleavagereaction c), at first the hydrogenation reaction a) is carried out, thenoptionally the cleavage reaction c) is carried out, and then theredistribution reaction b) is carried out, optionally in this embodimentafter the hydrogenation reaction a) the already formedmethylchlorohydridomonosilanes can be separated, before inducing thecleavage reaction c) and the redistribution reaction b), the silanesubstrate is selected from monosilanes, and such substrate is subjectedfirst to the hydrogenation reaction a), and subsequently to theredistribution reaction b), or such substrate is subjected to thehydrogenation reaction a), and the redistribution reaction b)simultaneously.
 11. The process of claim 1, wherein the silane substratecomprises a product of the Müller-Rochow Direct Process.
 12. Theprocess, of claim 1, wherein the silane substrate comprises the entireproduct of the Müller-Rochow Direct Process or a part (fraction) of theproduct of the Müller-Rochow Direct Process.
 13. The process, of claim1, wherein the silane substrate comprises the monosilane fraction of theMüller-Rochow Direct Process product.
 14. The process, of claim 1,wherein the silane substrate is the higher silane fraction (silaneshaving ≥2 Si atoms) of the Müller-Rochow Direct Process product.
 15. Theprocess, of claim 1, wherein the hydride donating source is LiH, andwhich process optionally comprises the step of separating the LiClformed and optionally the step of regeneration of LiH from the separatedLiCl.
 16. The process of claim 7, wherein the redistribution catalyst isselected from the group consisting of: R₄PCl, wherein R is hydrogen oran organyl group, which can be the same or different,triorganophosphines, wherein R is hydrogen or an organyl group,triorganoamines, wherein R is an organyl group, N-heterocyclic amines,quaternary ammonium compounds, an alkali metal halide, an alkaline earthmetal halide, an alkali metal hydride, and an alkaline earth metalhydride.
 17. The process of claim 7, wherein the cleavage catalyst isselected from the group consisting of: a quaternary Group 15 oniumcompound R₄QX, wherein each R is independently a hydrogen or an organylgroup, Q is phosphorus, arsenic, antimony or bismuth, and X is a halideselected from the group consisting of F, Cl, Br and I, a heterocyclicamine, a heterocyclic ammonium halide, a mixture of R₃P and RX, whereinR is as defined above, and X is as defined above, alkali metal halide,an alkaline earth metal halide, an alkali metal hydride, alkaline earthmetal hydride or mixtures thereof, optionally in the presence ofhydrogen chloride (HCl).